about facebook



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This article is about the website and its owner Facebook, Inc. For the photographic directory, see face book.
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Facebook, Inc.
Screenshot of Facebook’s home page.
Type Public
Traded as NASDAQFB
Foundation date CambridgeMassachusetts,U.S. (February 4, 2004)
Headquarters Menlo ParkCalifornia, U.S.
Area served United States (2004–05)
Worldwide (2005–present)
Key people Mark Zuckerberg
(Chairman and CEO)
Sheryl Sandberg
Industry Internet
Revenue Increase $5.1 billion (2012)[1]
Operating income Decrease US$ 538 million (2012)[2]
Net income Increase US$ 53 million (2012)[2]
Total assets Increase US$ 15.10 billion (2012)[2]
Total equity Increase US$ 11.75 billion (2012)[2]
Employees 4,900 (March,2013)[3]
Subsidiaries Instagram
Website facebook.com
Written in C++ and PHP[4]
Alexa rank Increase 1 (June 2013)[5]
Type of site Social networking service
Registration Required
Users 1.11 billion (active March 2013)[6]
Available in Multilingual (70)
Launched February 4, 2004
Current status Active

Facebook on the Ad-tech 2010

Facebook is an online social networking service, whose name stems from the colloquial name for the book given to students at the start of the academic year by some university administrations in the United States to help students get to know each other.[7] It was founded in February 2004 by Mark Zuckerberg with his college roommates and fellowHarvard University students Eduardo SaverinAndrew McCollumDustin Moskovitz andChris Hughes.[8] The website’s membership was initially limited by the founders to Harvard students, but was expanded to other colleges in the Boston area, the Ivy League, andStanford University. It gradually added support for students at various other universities before opening to high school students, and eventually to anyone aged 13 and over. Facebook now allows any users who declare themselves to be at least 13 years old to become registered users of the site.[9]

Users must register before using the site, after which they may create a personal profile, add other users as friends, exchange messages, and receive automatic notifications when they update their profile. Additionally, users may join common-interest user groups, organized by workplace, school or college, or other characteristics, and categorize their friends into lists such as “People From Work” or “Close Friends”. As of September 2012, Facebook has over one billion active users,[10] of which 8.7% are fake.[11] According to a May 2011 Consumer Reports survey, there are 7.5 million children under 13 with accounts and 5 million under 10, violating the site’s terms of service.[12]

In May 2005, Accel partners invested $12.7 million in Facebook, and Jim Breyer[13] added $1 million of his own money to the pot. A January 2009 Compete.com study ranked Facebook as the most used social networking service by worldwide monthly active users.[14] Entertainment Weekly included the site on its end-of-the-decade “best-of” list, saying, “How on earth did we stalk our exes, remember our co-workers’ birthdays, bug our friends, and play a rousing game of Scrabulous before Facebook?”[15] Facebook eventually filed for an initial public offering on February 1, 2012, and was headquartered in Menlo ParkCalifornia.[2] Facebook Inc. began selling stock to the public and trading on theNASDAQ on May 18, 2012.[16] Based on its 2012 income of USD 5.1 Billion, Facebook joined the Fortune 500 list for the first time, being placed at position of 462 on the list published in May 2013.[17]



Mark Zuckerberg wrote Facemash, the predecessor to Facebook, on October 28, 2003, while attending Harvard as a sophomore. According to The Harvard Crimson, the site was comparable to Hot or Not, and “used photos compiled from the online facebooks of nine houses, placing two next to each other at a time and asking users to choose the ‘hotter’ person”[18][19]

Mark Zuckerberg co-created Facebook in his Harvard dorm room.

To accomplish this, Zuckerberg hacked into the protected areas of Harvard’s computer network and copied the houses’ private dormitory ID images. Harvard at that time did not have a student “Facebook” (a directory with photos and basic information), though individual houses had been issuing their own paper facebooks since the mid-1980s. Facemash attracted 450 visitors and 22,000 photo-views in its first four hours online.[18][20]

The site was quickly forwarded to several campus group list-servers, but was shut down a few days later by the Harvard administration. Zuckerberg faced expulsion and was charged by the administration with breach of security, violating copyrights, and violating individual privacy. Ultimately, the charges were dropped.[21] Zuckerberg expanded on this initial project that semester by creating a social study tool ahead of an art history final, by uploading 500 Augustan images to a website, with one image per page along with a comment section.[20] He opened the site up to his classmates, and people started sharing their notes.

The following semester, Zuckerberg began writing code for a new website in January 2004. He was inspired, he said, by an editorial in The Harvard Crimson about the Facemash incident.[22] On February 4, 2004, Zuckerberg launched “Thefacebook”, originally located at thefacebook.com.[23]

Six days after the site launched, three Harvard seniors, Cameron WinklevossTyler Winklevoss, andDivya Narendra, accused Zuckerberg of intentionally misleading them into believing he would help them build a social network calledHarvardConnection.com, while he was instead using their ideas to build a competing product.[24] The three complained to the Harvard Crimson, and the newspaper began an investigation. The three later filed a lawsuit against Zuckerberg, subsequently settling.[25] The agreed settlement was for 1.2m shares which were worth $300m at Facebook’s IPO.[26]

Membership was initially restricted to students of Harvard College, and within the first month, more than half the undergraduate population at Harvard was registered on the service.[27] Eduardo Saverin (business aspects), Dustin Moskovitz (programmer), Andrew McCollum (graphic artist), and Chris Hughes soon joined Zuckerberg to help promote the website. In March 2004, Facebook expanded to Stanford, Columbia, and Yale.[28] It soon opened to the other Ivy League schools, Boston UniversityNew York UniversityMIT, and gradually most universities in Canada and the United States.[29][30]

In mid-2004, entrepreneur Sean Parker, who had been informally advising Zuckerberg, became the company’s president.[31] In June 2004, Facebook moved its base of operations to Palo Alto, California.[28] It received its first investment later that month from PayPal co-founder Peter Thiel.[32] The company dropped The from its name after purchasing the domain name facebook.com in 2005 for $200,000.[33]

Total active users[N 1]
Date Users
(in millions)
Days later Monthly growth[N 2]
August 26, 2008 100[34] 1,665 178.38%
April 8, 2009 200[35] 225 13.33%
September 15, 2009 300[36] 160 9.38%
February 5, 2010 400[37] 143 6.99%
July 21, 2010 500[38] 166 4.52%
January 5, 2011 600[39][N 3] 168 3.57%
May 30, 2011 700[40] 145 3.45%
September 22, 2011 800[41] 115 3.73%
April 24, 2012 900[42] 215 1.74%
October 4, 2012 1,000[43] 163 2.04%
March 31, 2013 1,110[6] 178 1.67%

Facebook launched a high-school version in September 2005, which Zuckerberg called the next logical step.[44] At that time, high-school networks required an invitation to join.[45] Facebook later expanded membership eligibility to employees of several companies, includingApple Inc. and Microsoft.[46] Facebook was then opened on September 26, 2006, to everyone of age 13 and older with a valid email address.[47][48]

Late in 2007, Facebook had 100,000 business pages, allowing companies to attract potential customers and tell about themselves. These started as group pages, but a new concept called company pages was planned.[49]

On October 24, 2007, Microsoft announced that it had purchased a 1.6% share of Facebook for $240 million, giving Facebook a total implied value of around $15 billion.[50] Microsoft’s purchase included rights to place international ads on Facebook.[51] In October 2008, Facebook announced that it would set up its international headquarters in Dublin, Ireland.[52] In September 2009, Facebook said that it had turned cash-flow positive for the first time.[53] In November 2010, based on SecondMarket Inc., an exchange for shares of privately held companies, Facebook’s value was $41 billion (slightly surpassing eBay‘s) and it became the third largest U.S. Web company after Google and Amazon.[54]

Traffic to Facebook increased steadily after 2009. More people visited Facebook than Google for the week ending March 13, 2010.[55]

In March 2011, it was reported that Facebook removes approximately 20,000 profiles from the site every day for various infractions, including spam, inappropriate content and underage use, as part of its efforts to boost cyber security.[56]

In early 2011, Facebook announced plans to move to its new headquarters, the former Sun Microsystems campus in Menlo Park, California.[57][58]

Release of statistics by DoubleClick showed that Facebook reached one trillion page views in the month of June 2011, making it the most visited website of those tracked by DoubleClick.[59]

According to the Nielsen Media Research study, released in December 2011, Facebook is the second most accessed website in the US (behind Google).[60]

In March 2012, Facebook announced App Center, an online mobile store which sells applications that connect to Facebook. The store will be available to iPhoneAndroid and mobile web users.[61]

Facebook, Inc. held an initial public offering on May 17, 2012, negotiating a share price of $38 apiece, valuing the company at $104 billion, the largest valuation to date for a newly listed public company.[62]

Initial public offering

Main article: Facebook IPO

An electronic billboard on theThomson Reuters building welcomes Facebook to the Nasdaq.

Facebook filed their S1 document with the Securities and Exchange Commission (SEC) on February 1, 2012. The company filed for a US$5 billion initial public offering (IPO), making it one of the biggest in tech history and the biggest in Internet history.[63] Facebook valued its stock at $38 a share, pricing the company at $104 billion, the largest valuation to date for a newly public company.[64] The IPO raised $16 billion, making it the third largest in U.S. history.[65][66] The shares began to be traded on May 18, and though the stock struggled to stay above the IPO price for most of the day, it set a new record for trading volume of an IPO, 460 million shares.[67] The first day of trading was marred by numerous technical glitches that prevented orders from going through.[68] Only the aforementioned technical glitches and artificial support from underwriters prevented the stock price from falling below the IPO price on the first day of trading.[69]

Later, it was revealed that Facebook’s lead underwriters, Morgan Stanley (MS), JP Morgan (JPM), and Goldman Sachs (GS) all cut their earnings forecasts for the company in the middle of the IPO roadshow.[70] The stock continued its freefall in subsequent days, closing at 34.03 on May 21 and 31.00 on May 22. A ‘circuit breaker’ was used in an attempt to slow down the decline in the stock price.[71] Securities and Exchange Commission Chairman Mary Schapiro and Financial Industry Regulatory Authority (FINRA) Chairman Rick Ketchum called for a review of the circumstances surrounding its troubled initial public offering.[72]

Facebooks’ IPO is now under investigation and has been compared to pump and dump schemes.[68][70][72][73] In the meantime, a class-action lawsuit is in the works due to the trading glitches, which led to botched orders.[74][75] Apparently, the glitches prevented a number of investors from selling the stock during the first day of trading while the stock price was falling – forcing them to incur bigger losses when their trades finally went through.

Additional lawsuits have been filed due to allegations that an underwriter for Morgan Stanley selectively revealed adjusted earnings estimates to preferred clients. The remaining underwriters (MS, JPM, GS) and Facebook’s CEO and board are also facing litigation.[76]It is believed that adjustments to earnings estimates were communicated to the underwriters by a Facebook financial officer, who in turn used the information to cash out on their positions while leaving the general public with overpriced shares.[77]

By the end of May 2012, the stock lost over a quarter of its starting value, which led to the Wall Street Journal calling the IPO a “fiasco.”[78]

After IPO

In July 2012, Facebook added a gay marriage icon to its timeline feature.[79] On August 23, 2012, Facebook released an update to its iOS app, version 5.0. The app changed how data was collected and displayed to make the app faster. On January 15, 2013, Facebook announced its new product Graph Search, which provides users with a “precise answer” rather than a link to an answer by leveraging the data already present on its site.[80] Facebook emphasized that the feature would be “privacy-aware,” returning only results from content already shared with the user.[81] The company is the subject of a lawsuit by Rembrandt Social Media for the use of patents involving the “Like” button.[82] On April 3, 2013, Facebook unveiled Home, a user-interface layer for Android devices offering greater integration with the service. HTC announced a smartphone with Home pre-loaded, the HTC First.[83] On April 15, 2013, Facebook announced an alliance with the National Association of Attorneys General to provide teens and parents with information on tools that to manage Facebook profiles. The partnership spanned 19 states.[84] On April 19, 2013, Facebook officially modfied its logo to remove the faint blue line at the bottom of the “F” icon. The letter “F” moved closer to the edge of the box.[85]

Following a campaign uniting 100 advocacy groups, Facebook agreed to update its policy on hate speech. The campaign highlighted content promoting domestic and sexual violence against women, and used over 57,000 tweets and more than 4,900 emails to create outcomes such as the withdrawal of advertising from Facebook by 15 companies, including Nissan UK, House of Burlesque and Nationwide UK. The social media website initially responded by stating that “While it may be vulgar and offensive, distasteful content on its own does not violate our policies.”,[86] but agreed on May 29, 2013 to take action after it had “become clear that our systems to identify and remove hate speech have failed to work as effectively as we would like, particularly around issues of gender-based hate.”[87]

On June 12, 2013 Facebook officially announced on its newsroom that it was introducing clickable hashtags to help users follow trending discussions or search what others are talking about on a particular topic.[88] A July 2013 Wall Street Journal article identified the Facebook IPO as the cause of a change in the U.S.’ national economic statistics, as the company home, San Mateo County, California, became the top wage-earning county in the country after the fourth quarter of 2012. The Bureau of Labor Statistics reported that the average weekly wage in the county was US$3,240, 107% higher than the previous year: “That’s the equivalent of $168,000 a year, and more than more than 50% higher than the next highest county, New York County (better known as Manhattan), which came in at $2,107 a week, or roughly $110,000 a year.”[89]

Corporate affairs


The ownership percentages of the company, As of 2012 are: Mark Zuckerberg: 28%,[90] Accel Partners: 10%, Digital Sky Technologies: 10%,[91] Dustin Moskovitz: 6%, Eduardo Saverin: 5%, Sean Parker: 4%, Peter Thiel: 3%, Greylock Partners andMeritech Capital Partners: between 1 to 2% each, Microsoft: 1.3%, Li Ka-shing: 0.8%, the Interpublic Group: less than 0.5%. A small group of current and former employees and celebrities own less than 1% each, including Matt Cohler, Jeff Rothschild, Adam D’Angelo, Chris Hughes, and Owen Van Natta, while Reid Hoffman and Mark Pincus have sizable holdings of the company. The remaining 30% or so are owned by employees, an undisclosed number of celebrities, and outside investors.[92] Adam D’Angelo, former chief technology officer and friend of Zuckerberg, resigned in May 2008. Reports claimed that he and Zuckerberg began quarreling, and that he was no longer interested in partial ownership of the company.[93]

Key management personnel comprise Chris Cox (VP of Product), Sheryl Sandberg (COO), and Mark Zuckerberg (Chairman and CEO). As of April 2011, Facebook has over 2,000 employees, and offices in 15 countries.[94] Other managers include chief financial officer David Ebersman and public relations head Elliot Schrage.[95]


Most of Facebook’s revenue comes from advertising.[96][97]

(estimated, in millions US$)
Year Revenue Growth
2006 $52[98]
2007 $150[99] 188%
2008 $280[100] 87%
2009 $775[101] 177%
2010 $2,000[102] 158%
2011 $4,270[103] 114%

Facebook generally has a lower clickthrough rate (CTR) for advertisements than most major Web sites. According to BusinessWeek.com, banner advertisements on Facebook have generally received one-fifth the number of clicks compared to those on the Web as a whole,[104] although specific comparisons can reveal a much larger disparity. For example, while Google users click on the first advertisement for search results an average of 8% of the time (80,000 clicks for every one million searches),[105] Facebook’s users click on advertisements an average of 0.04% of the time (400 clicks for every one million pages).[106]

Sarah Smith, who was Facebook’s Online Sales Operations Manager, reports that successful advertising campaigns on the site can have clickthrough rates as low as 0.05% to 0.04%, and that CTR for ads tend to fall within two weeks.[107] By comparison, the CTR for competing social network MySpace is about 0.1%, about 2.5 times better than Facebook’s rate but still low compared to many other Web sites. The cause of Facebook’s low CTR has been attributed to younger users enabling ad blocking software and being better at ignoring advertising messages, as well as the site being used more for the purpose of social communication as opposed to viewing content.[108]

On pages for brands and products, however, some companies have reported CTR as high as 6.49% for Wall posts.[109] A study found that, for video advertisements on Facebook, over 40% of users who viewed the videos viewed the entire video, while the industry average was 25% for in-banner video ads.[110]

Mergers and acquisitions

On November 15, 2010, Facebook announced it had acquired the domain name fb.com from the American Farm Bureau Federation for an undisclosed amount. On January 11, 2011, the Farm Bureau disclosed $8.5 million in “domain sales income”, making the acquisition of FB.com one of the ten highest domain sales in history.[111]


Entrance to Facebook headquarters complex in Menlo Park, California

Entrance to Facebook’s previous headquarters in the Stanford Research Park,Palo AltoCalifornia

In early 2011, Facebook announced plans to move to its new headquarters, the former Sun Microsystems campus in Menlo ParkCalifornia.

All users outside of the US and Canada have a contract with Facebook’s Irish subsidiary “Facebook Ireland Limited”. This allows Facebook to avoid US taxes for all users in Europe, Asia, Australia, Africa and South America. Facebook is making use of the Double Irish arrangement which allows it to pay just about 2-3% corporation tax on all international revenue.[112]

In 2010, Facebook opened its fourth office, in Hyderabad[113][114][115] and the first inAsia.[116]

Facebook, which in 2010 had more than 750 million active users globally including over 23 million in India, announced that its Hyderabad centre would house online advertising and developer support teams and provide round-the-clock, multi-lingual support to the social networking site’s users and advertisers globally.[117] With this, Facebook joins other giants like GoogleMicrosoftOracleDellIBM and Computer Associates that have already set up shop.[118] In Hyderabad, it is registered as ‘Facebook India Online Services Pvt Ltd’.[119][120][121]

Though Facebook did not specify its India investment or hiring figures, it said recruitment had already begun for a director of operations and other key positions at Hyderabad,[122]which would supplement its operations in CaliforniaDublin in Ireland as well as at Austin,Texas.

A custom-built data center with substantially reduced (“38% less”) power consumptioncompared to existing Facebook data centers opened in April 2011 in Prineville, Oregon.[123]

In April 2012 Facebook opened a second data center in Forest City, North Carolina.

On October 1, 2012, CEO Zuckerberg visited Moscow to stimulate social media innovation in Russia and to boost Facebook’s position in the Russian market.[124] Russia’s communications minister tweeted that Prime Minister Dmitry Medvedev urged the social media giant’s founder to abandon plans to lure away Russian programmers and instead consider opening a research center in Moscow. Facebook has roughly 9 million users in Russia, while domestic clone VK has around 34 million.[125]

Open source contributions

Facebook is both a consumer of and contributor to free and open source software.[126] Facebook’s contributions include: HipHop for PHP,[127] Fair scheduler in Apache Hadoop,[128] Apache HiveApache Cassandra,[129] and the Open Compute Project.[130]

Facebook also contributes to other opensource projects such as Oracle‘s MySQL database engine.[131][132]


Main articles: Facebook features and Facebook Platform

Profile shown on Thefacebook in 2005

User profile

Users can create profiles with photos, lists of personal interests, contact information, and other personal information. Users can communicate with friends and other users through private or public messages and a chat feature. They can also create and join interest groups and “like pages” (called “fan pages” until April 19, 2010), some of which are maintained by organizations as a means of advertising.[133] Facebook has been prompted to add a “third gender“, “other”, or “intersex” tab in the gender option which contains only male and female.[134] Facebook refused and said that individuals can “opt out of showing their sex on their profile”.[135] A 2012 Pew Internet and American Life study identified that between 20–30% of Facebook users are “power users” who frequently link, poke, post and tag themselves and others.[136] The user page is set up in a minimal fashion with blue as the main color. This was done because Zuckerberg is red-green colorblind.[137]

On June 13, 2009, Facebook introduced a “Usernames” feature, whereby pages can be linked with simpler URLs such ashttp://www.facebook.com/facebook instead of http://www.facebook.com/profile.php?id=20531316728.[138]Many new smartphones offer access to Facebook services through either their Web browsers or applications. An official Facebook application is available for the operating systems AndroidiOS, and webOSNokia and Research In Motion both provide Facebook applications for their own mobile devices. More than 425 million active users access Facebook through mobile devices across 200 mobile operators in 60 countries.[139]

Comparison with Myspace

The media often compares Facebook to Myspace, but one significant difference between the two Web sites is the level of customization.[140] Another difference is Facebook’s requirement that users give their true identity, a demand that MySpace does not make.[141] MySpace allows users to decorate their profiles using HTML and Cascading Style Sheets (CSS), while Facebook allows only plain text.[142] Facebook has a number of features with which users may interact. They include the Wall, a space on every user’s profile page that allows friends to post messages for the user to see;[143] Pokes, which allows users to send a virtual “poke” to each other (a notification then tells a user that they have been poked);[144] Photos, where users can upload albums and photos;[145] andStatus, which allows users to inform their friends of their whereabouts and actions.[146] Depending on privacy settings, anyone who can see a user’s profile can also view that user’s Wall. In July 2007, Facebook began allowing users to post attachments to the Wall, whereas the Wall was previously limited to textual content only.[143]

News feed

On September 6, 2006, a News feed was announced, which appears on every user’s homepage and highlights information including profile changes, upcoming events, and birthdays of the user’s friends.[147] This enabled spammers and other users to manipulate these features by creating illegitimate events or posting fake birthdays to attract attention to their profile or cause.[148] Initially, the News Feed caused dissatisfaction among Facebook users; some complained it was too cluttered and full of undesired information, others were concerned that it made it too easy for others to track individual activities (such as relationship status changes, events, and conversations with other users).[149]

In response, Zuckerberg issued an apology for the site’s failure to include appropriate customizable privacy features. Since then, users have been able to control what types of information are shared automatically with friends. Users are now able to prevent user-set categories of friends from seeing updates about certain types of activities, including profile changes, Wall posts, and newly added friends.[150]

On February 23, 2010, Facebook was granted a patent[151] on certain aspects of its News Feed. The patent covers News Feeds in which links are provided so that one user can participate in the same activity of another user.[152] The patent may encourage Facebook to pursue action against websites that violate its patent, which may potentially include websites such as Twitter.[153]

One of the most popular applications on Facebook is the Photos application, where users can upload albums and photos.[154]Facebook allows users to upload an unlimited number of photos, compared with other image hosting services such as Photobucket andFlickr, which apply limits to the number of photos that a user is allowed to upload. During the first years, Facebook users were limited to 60 photos per album. As of May 2009, this limit has been increased to 200 photos per album.[155][156][157][158]

Privacy settings can be set for individual albums, limiting the groups of users that can see an album. For example, the privacy of an album can be set so that only the user’s friends can see the album, while the privacy of another album can be set so that all Facebook users can see it. Another feature of the Photos application is the ability to “tag“, or label, users in a photo. For instance, if a photo contains a user’s friend, then the user can tag the friend in the photo. This sends a notification to the friend that they have been tagged, and provides them a link to see the photo.[159]

On June 7, 2012, Facebook launched its App Center to its users. It will help the users in finding games and other applications with ease.[160] Since the launch of the App Center, Facebook has seen 150M monthly users with 2.4 times the installation of apps.[161]

The sorting and display of stories in a user’s News Feed is governed by the algorithm EdgeRank.[162]

Facebook Notes

Facebook Notes was introduced on August 22, 2006, a blogging feature that allowed tags and embeddable images. Users were later able to import blogs from XangaLiveJournalBlogger, and other blogging services.[47] During the week of April 7, 2008, Facebook released a Comet-based[163] instant messaging application called “Chat” to several networks,[164] which allows users to communicate with friends and is similar in functionality to desktop-based instant messengers.

Facebook launched Gifts on February 8, 2007, which allows users to send virtual gifts to their friends that appear on the recipient’s profile. Gifts cost $1.00 each to purchase, and a personalized message can be attached to each gift.[165][166] On May 14, 2007, Facebook launched Marketplace, which lets users post free classified ads.[167] Marketplace has been compared to Craigslist by CNET, which points out that the major difference between the two is that listings posted by a user on Marketplace are seen only by users in the same network as that user, whereas listings posted on Craigslist can be seen by anyone.[168]

On July 20, 2008, Facebook introduced “Facebook Beta”, a significant redesign of its user interface on selected networks. The Mini-Feed and Wall were consolidated, profiles were separated into tabbed sections, and an effort was made to create a “cleaner” look.[169]After initially giving users a choice to switch, Facebook began migrating all users to the new version starting in September 2008.[170]On December 11, 2008, it was announced that Facebook was testing a simpler signup process.[171]


A new Messaging platform, codenamed “Project Titan”, was launched on November 15, 2010. Described as a “Gmail killer” by some publications, the system allows users to directly communicate with each other via Facebook using several different methods (including a special email address, text messaging, or through the Facebook website or mobile app)—no matter what method is used to deliver a message, they are contained within single threads in a unified inbox. As with other Facebook features, users can adjust from whom they can receive messages from—including just friends, friends of friends, or from anyone.[172][173]

Aside from the Facebook website, Messages can also be accessed through the site’s mobile apps, or a dedicated Facebook Messenger app,[174]

Voice calls

Since April 2011, Facebook users have had the ability to make live voice calls via Facebook Chat, allowing users to chat with others from all over the world. This feature, which is provided free through T-Mobile’s new Bobsled service, lets the user add voice to the current Facebook Chat as well as leave voice messages on Facebook.[175]

Video calling

On July 6, 2011, Facebook launched its video calling services using Skype as its technology partner. It allows one-to-one calling using a Skype Rest API.


On September 14, 2011, Facebook added the ability for users to provide a “Subscribe” button on their page, which allows users to subscribe to public postings by the user without needing to add them as a friend.[176] In conjunction, Facebook also introduced a system in February 2012 to verify the identity of certain accounts. Unlike a similar system used by Twitter, verified accounts do not display a special verification badge, but are given a higher priority in a user’s “Subscription Suggestions”.[177]

In December 2012, Facebook announced that due to user confusion surrounding its function, the Subscribe button would be re-labeled as a “Follow” button—making it more similar to other social networks with similar functions.[178]


To allay concerns about privacy, Facebook enables users to choose their own privacy settings and choose who can see specific parts of their profile.[179] The website is free to users, and generates revenue from advertising, such as banner ads.[180] Facebook requires a user’s name and profile picture (if applicable) to be accessible by everyone. Users can control who sees other information they have shared, as well as who can find them in searches, through their privacy settings.[181]

According to comScore, an internet marketing research company, Facebook collects as much data from its visitors as Google and Microsoft, but considerably less than Yahoo!.[182] In 2010, the security team began expanding its efforts to reduce the risks to users’privacy,[183] but privacy concerns remain.[184] On November 6, 2007, Facebook launched Facebook Beacon, which was an ultimately failed attempt to advertise to friends of users using the knowledge of what purchases friends made. As of March 2012, Facebook’s usage of its user data is under close scrutiny.[185]

FTC settlement

On November 29, 2011, Facebook agreed to settle US Federal Trade Commission charges that it deceived consumers by failing to keep privacy promises.[186]

Technical aspects

Facebook is built in PHP which is compiled with HipHop for PHP, a source code transformer built by Facebook engineers that turns PHP into C++. The deployment of HipHop reportedly reduced average CPU consumption on Facebook servers by 50%.[187]

Facebook is developed as one monolithic application. According to an interview in 2012 with Chuck Rossi, a build engineer at Facebook, Facebook compiles into a 1.5 GB binary blob which is then distributed to the servers using a custom BitTorrent-based release system. Rossi stated that it takes approximately 15 minutes to build and 15 minutes to release to the servers. The build and release process is zero downtime and new changes to Facebook are rolled out daily.[187]

Facebook used a combination platform based on HBase to store data across distributed machines. Using a tailing architecture, new events are stored in log files, and the logs are tailed. The system rolls these events up and writes them into storage. The User Interface then pulls the data out and displays it to users. Facebook handles requests as AJAX behavior. These requests are written to a log file using Scribe (developed by Facebook).[188]

Data is read from these log files using Ptail, an internally built tool to aggregate data from multiple Scribe stores. It tails the log files and pulls data out (thus the name). Ptail data is separated out into three streams so they can eventually be sent to their own clusters in different data centers (Plugin impression, News feed impressions, Actions (plugin + news feed)). Puma is used to manage periods of high data flow (Input/Output or IO). Data is processed in batches to lessen the amount of times needed to read and write under high demand periods (A hot article will generate a lot of impressions and news feed impressions which will cause huge data skews). Batches are taken every 1.5 seconds, limited by memory used when creating a hash table.[188]

After this, data is output in PHP format (compiled with HipHop for PHP). The backend is written in Java and Thrift is used as the messaging format so PHP programs can query Java services. Caching solutions are used to make the web pages display more quickly. The more and longer data is cached the less realtime it is. The data is then sent to MapReduce servers so it can be queried via Hive. This also serves as a backup plan as the data can be recovered from Hive. Raw logs are removed after a period of time.[188]

Like button

The like button is a social networking feature, allowing users to express their appreciation of content such as status updates, comments, photos, and advertisements. It is also a social plug-in of the Facebook Platform – launched on April 21, 2010[189][190] – that enables participating Internet websites to display a similar like button.

Continuously liking any contents of one’s friend will cause flooding of notifications on his/her part and Facebook will display message to the liker stating that (s)he must slow down; (s)he must wait for five minutes in order for him/her to continue liking.


Patents relating to the “Like” button and other social features held by deceased Dutch programmer Joannes Jozef Everardus van Der Meer are subject of a lawsuit brought against Facebook by Rembrandt Social Media.[82]


Facebook popularity. Active users of Facebook increased from just a million in 2004 to over 750 million in 2011.[191]

Registered Facebook users by age as of 2010.

According to comScore, Facebook is the leading social networking site based on monthly unique visitors, having overtaken main competitor MySpace in April 2008.[192] ComScore reports that Facebook attracted 130 million unique visitors in May 2010, an increase of 8.6 million people.[193] According to Alexa, the website’s ranking among all websites increased from 60th to 7th in worldwide traffic, from September 2006 to September 2007, and is currently 2nd.[194]Quantcast ranks the website 2nd in the U.S. in traffic,[195] and Compete.comranks it 2nd in the U.S.[196] The website is the most popular for uploading photos, with 50 billion uploaded cumulatively.[197] In 2010, Sophos‘s “Security Threat Report 2010” polled over 500 firms, 60% of which responded that they believed that Facebook was the social network that posed the biggest threat to security, well ahead of MySpace, Twitter, and LinkedIn.[183]

Facebook is the most popular social networking site in several English-speaking countries, including Canada,[198] the United Kingdom,[199] and the United States.[200][201][202][203] In regional Internet markets, Facebook penetration is highest in North America (69 percent), followed by Middle East-Africa (67 percent), Latin America (58 percent), Europe (57 percent), and Asia-Pacific (17 percent).[204] Some of the top competitors were listed in 2007 by Mashable.[205]

The website has won awards such as placement into the “Top 100 Classic Websites” by PC Magazine in 2007,[206] and winning the “People’s Voice Award” from the Webby Awards in 2008.[207] In a 2006 study conducted by Student Monitor, a New Jersey-based company specializing in research concerning the college student market, Facebook was named the second most popular thing among undergraduates, tied with beer and only ranked lower than the iPod.[208]

On March 2010, Judge Richard Seeborg issued an order approving the class settlement in Lane v. Facebook, Inc., the class action lawsuit arising out of Facebook’s Beacon program.

In 2010, Facebook won the Crunchie “Best Overall Startup Or Product” for the third year in a row[209] and was recognized as one of the “Hottest Silicon ValleyCompanies” by Lead411.[210] However, in a July 2010 survey performed by the American Customer Satisfaction Index, Facebook received a score of 64 out of 100, placing it in the bottom 5% of all private-sector companies in terms of customer satisfaction, alongside industries such as the IRS e-file system, airlines, and cable companies. The reasons why Facebook scored so poorly include privacy problems, frequent changes to the website’s interface, the results returned by the News Feed, and spam.[211]

In December 2008, the Supreme Court of the Australian Capital Territory ruled that Facebook is a valid protocol to serve court notices to defendants. It is believed to be the world’s first legal judgement that defines a summons posted on Facebook as legally binding.[212] In March 2009, the New Zealand High Court associate justice David Gendall allowed for the serving of legal papers on Craig Axe by the company Axe Market Garden via Facebook.[213][214] Employers (such as Virgin Atlantic Airways) have also used Facebook as a means to keep tabs on their employees and have even been known to fire them over posts they have made.[215]

By 2005, the use of Facebook had already become so ubiquitous that the generic verb “facebooking” had come into use to describe the process of browsing others’ profiles or updating one’s own.[216] In 2008, Collins English Dictionary declared “Facebook” as its new Word of the Year.[217] In December 2009, the New Oxford American Dictionary declared its word of the year to be the verb “unfriend“, defined as “To remove someone as a ‘friend‘ on a social networking site such as Facebook. As in, ‘I decided to unfriend my roommate on Facebook after we had a fight.'”[218]

In early 2010, Openbook was established, an avowed parody (and privacy advocacy) website[219] that enables text-based searches of those Wall posts that are available to “Everyone”, i.e. to everyone on the Internet.

Writers for The Wall Street Journal found in 2010 that Facebook apps were transmitting identifying information to “dozens of advertising and Internet tracking companies”. The apps used an HTTP referrer which exposed the user’s identity and sometimes their friends’. Facebook said, “We have taken immediate action to disable all applications that violate our terms”.[220]

In January 2013, the countries with the most Facebook users were:[221]

  • United States with 168.8 million members
  • Brazil with 64.6 million members
  • India with 62.6 million members
  • Indonesia with 51.4 million members
  • Mexico with 40.2 million members

All of the above total 309 million members or about 38.6 percent of Facebook’s 1 billion worldwide members.[222] As of March 2013, Facebook reported having 1.11 billion monthly active users, globally. [223]

In regards to Facebook’s mobile usage, per an analyst report in early 2013, there are 192 million Android users, 147 million iPhone users, 48 million iPad users and 56 million messenger users, and a total of 604 million mobile Facebook users.[224]


Main article: Criticism of Facebook

Facebook has met with controversies. It has been blocked intermittently in several countries including the People’s Republic of China,[225] Iran,[226] Uzbekistan,[227] Pakistan,[228] Syria (unblocked in Syria[229]),[230] and Bangladesh[citation needed] on different bases. For example, it was banned in many countries of the world on the basis of allowed content judged as anti-Islamic and containing religious discrimination. It has also been banned at many workplaces to prevent employees from using it during work hours.[231] Theprivacy of Facebook users has also been an issue, and the safety of user accounts has been compromised several times. Facebook has settled a lawsuit regarding claims over source code and intellectual property.[232] In May 2011 emails were sent to journalists and bloggers making critical allegations about Google’s privacy policies; however it was later discovered that the anti-Google campaign, conducted by PR giant Burson-Marsteller, was paid for by Facebook in what CNN referred to as “a new level skullduggery” and which Daily Beast called a “clumsy smear“.[233]

In July 2011, German authorities began to discuss the prohibition of events organized on Facebook. The decision is based on several cases of overcrowding by people not originally invited.[234][235] In one instance, 1,600 “guests” attended the 16th birthday party for a Hamburg girl who accidentally posted the invitation for the event as public. After reports of overcrowding, more than a hundred police were deployed for crowd control. A policeman was injured and eleven participants were arrested for assault, property damage and resistance to authorities.[236] In another unexpectedly overcrowded event, 41 young people were arrested and at least 16 injured.[237]

In 2007, it was reported that 43% of British office workers were blocked from accessing Facebook at work, due to concerns including reduced productivity and the potential for industrial espionage.[238]

A 2011 study in the online journal First Monday, “Why Parents Help Their Children Lie to Facebook About Age: Unintended Consequences of the Children’s Online Privacy Protection Act,” examines how parents consistently enable children as young as 10 years old to sign up for accounts, directly violating Facebook’s policy banning young visitors. This policy technically allows Facebook to avoid conflicts with a United States federal law, the 1998 Children’s Online Privacy Protection Act (COPPA), which requires minors aged 13 or younger to gain explicit parental consent to access commercial websites. Of the more than 1,000 households surveyed for the study, more than three-quarters (76%) of parents reported that their child joined Facebook when she was younger than 13, the minimum age in the site’s terms of service. The study notes that, in response to widespread reports of underage users, a Facebook executive has said that “Facebook removes 20,000 people a day, people who are underage.” The study’s authors also note, “Indeed, Facebook takes various measures both to restrict access to children and delete their accounts if they join.” The findings of the study raise questions primarily about the shortcomings of United States federal law, but also implicitly continue to raise questions about whether or not Facebook does enough to publicize its terms of service with respect to minors. Only 53% of parents said they were aware that Facebook has a minimum signup age; 35% of these parents believe that the minimum age is a site recommendation (not a condition of site use), or thought the signup age was 16 or 18, and not 13.[239]

In November 2011, several Facebook users in Bangalore, India reported that their accounts had been hacked and their profile pictures were replaced with pornographic images. For more than a week, users’ news feeds were spammed with pornographic, violent and sexual contents, and it was reported that more than 200,000 accounts were affected. Facebook described the reports as inaccurate, and Bangalore police speculated that the stories may have been rumors spread by Facebook’s competitors.[240][241]

A 2013 study in the journal CyberPsychology, Behavior, and Social Networking, “Who Commits Virtual Identity Suicide? Differences in Privacy Concerns, Internet Addiction, and Personality Between Facebook Users and Quitters” points to the fact that there is a rising number of Facebook users who are discontent with Facebook and finally decide to quit Facebook. The number one reason for users to quit Facebook was privacy concerns (48%), being followed by a general dissatisfaction with Facebook (14%), negative aspects regarding Facebook friends (13%) and the feeling of getting addicted to Facebook (6%). Facebook quitters were found to be more concerned about privacy, more addicted to the Internet and more conscientious.[184]


Media impact

In April 2011, Facebook launched a new portal for marketers and creative agencies to help them develop brand promotions on Facebook.[242] The company began its push by inviting a select group of British advertising leaders to meet Facebook’s top executives at an “influencers’ summit” in February 2010. Facebook has now been involved in campaigns for True BloodAmerican Idol, and Top Gear.[243] News and media outlets such as the Washington Post,[244] Financial Times[245] and ABC News[246] have used aggregated Facebook fan data to create various infographics and charts to accompany their articles. In 2012, the beauty pageant Miss Sri Lanka Online was run exclusively using Facebook.[247]

Social impact

Facebook has affected the social life and activity of people in various ways. With its availability on many mobile devices, Facebook allows users to continuously stay in touch with friends, relatives and other acquaintances wherever they are in the world, as long as there is access to the Internet. It can also unite people with common interests and/or beliefs through groups and other pages, and has been known to reunite lost family members and friends because of the widespread reach of its network.[248] One such reunion was between John Watson and the daughter he had been seeking for 20 years. They met after Watson found her Facebook profile.[249]Another father–daughter reunion was between Tony Macnauton and Frances Simpson, who had not seen each other for nearly 48 years.[250]

Some argue that Facebook is beneficial to one’s social life because they can continuously stay in contact with their friends and relatives, while others say that it can cause increased antisocial tendencies because people are not directly communicating with each other. Some studies have named Facebook as a source of problems in relationships. Several news stories have suggested that using Facebook can lead to higher instances of divorce and infidelity, but the claims have been questioned by other commentators.[251][252]

Facebook envy

Recent studies have shown that Facebook causes negative effects on self-esteem by triggering feelings of envy, with vacation and holiday photos proving to be the largest resentment triggers. Other prevalent causes of envy include posts by friends about family happiness and images of physical beauty—such envious feelings leave people lonely and dissatisfied with their own lives. A joint study by two German universities discovered that one out of three people were more dissatisfied with their lives after visiting Facebook, and another study by Utah Valley University found that college students felt worse about their own lives following an increase in the amount of time spent on Facebook.[253][254][255]

Political impact

The stage at the Facebook – Saint Anselm College debates in 2008.

Facebook’s role in the American political process was demonstrated in January 2008, shortly before the New Hampshire primary, when Facebook teamed up with ABC and Saint Anselm College to allow users to give live feedback about the “back to back” January 5 Republican and Democratic debates.[256][257][258] Charles Gibson moderated both debates, held at the Dana Center for the Humanities at Saint Anselm College. Facebook users took part in debate groups organized around specific topics, register to vote, and message questions.[259]

ABCNews.com reported in 2012 that the Facebook fanbases of political candidates have relevance for the election campaign, including:

  • Allows politicians and campaign organizers to understand the interests and demographics of their Facebook fanbases, to better target their voters.
  • Provides a means for voters to keep up-to-date on candidates’ activities, such as connecting to the candidates’ Facebook Fan Pages.

Unless you get out of Facebook and into someone’s face, you really have not acted.

Over a million people installed the Facebook application “US Politics on Facebook” in order to take part, and the application measured users’ responses to specific comments made by the debating candidates.[261] This debate showed the broader community what many young students had already experienced: Facebook as a popular and powerful new way to interact and voice opinions. An article by Michelle Sullivan of Uwire.com illustrates how the “Facebook effect” has affected youth voting rates, support by youth of political candidates, and general involvement by the youth population in the 2008 election.[262]

In February 2008, a Facebook group called “One Million Voices Against FARC” organized an event in which hundreds of thousands of Colombians marched in protest against the Revolutionary Armed Forces of Colombia, better known as the FARC (from the group’s Spanish name).[263] In August 2010, one of North Korea’s official government websites and the official news agency of the country,Uriminzokkiri, joined Facebook.[264]

A man during the 2011 Egyptian protests carrying a card saying “Facebook, #jan25, The Egyptian Social Network”.

In January 2011, Facebook played a major role in generating the first spark for the 2011 Egyptian revolution.[265][266] On January 14, the Facebook page of “We are all khaled Said” was started by Wael Ghoniem Create Event to invite the Egyptian people to “peaceful demonstrations” on January 25. As in Tunisia, Facebook become the primary tool for connecting all protesters, which lead the Egyptian government of Prime Minister Nazif to ban Facebook, Twitter and another websites on January 26[267] then ban all mobile and Internet connections for all of Egypt at midnight January 28. After 18 days, the uprising forced President Mubarak to resign.

In 2011 there was a controversial ruling by French government to uphold a 1992 decree which stipulates that commercial enterprises should not be promoted on news programs. President Nicolas Sarkozy’s colleagues have agreed that it will enforce a law so that the word “Facebook” will not be allowed to be spoken on the television or on the radio.[268]

In 2011, Facebook filed paperwork with the Federal Election Commission to form a political action committee under the name FB PAC.[269] In an email to The Hill, a spokesman for Facebook said “FB PAC will give our employees a way to make their voice heard in the political process by supporting candidates who share our goals of promoting the value of innovation to our economy while giving people the power to share and make the world more open and connected.”[270]

In popular culture

See also


  1. ^ An “active user” is defined by Facebook as a user who has visited the website in the last 30 days.
  2. ^ “Monthly growth” is the average percentage growth rate at which the total number of active users grows each month over the specified period.
  3. ^ This value is from an investment document. The date is from when the document was revealed to the public, not the actual date that the website reached this many users.


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about google



From Wikipedia, the free encyclopedia
This article is about the corporation. For the search engine, see Google Search. For other uses, see Google (disambiguation).
Not to be confused with Googol.
Page semi-protected
Google Inc.
Google Logo
Type Public
NASDAQ-100 Component
S&P 500 Component
Industry Internet
Computer software
Telecoms equipment
Founded Menlo Park, California
(September 4, 1998)[1][2]
Founder(s) Larry Page, Sergey Brin
Headquarters Googleplex, Mountain View, California, United States
Area served Worldwide
Key people Eric Schmidt
(Executive Chairman)
Larry Page
(Co-founder & CEO)
Sergey Brin (Co-founder)
Products See list of Google products
Revenue Increase US$ 50.18 billion (2012)[3]
Operating income Increase US$ 12.76 billion (2012)[3]
Profit Increase US$ 10.74 billion (2012)[3]
Total assets Increase US$ 93.80 billion (2012)[3]
Total equity Increase US$ 71.72 billion (2012)[3]
Employees 44,777 (Q2 2013)[4]
Subsidiaries AdMob, DoubleClick, Motorola Mobility, On2 Technologies, Picnik, YouTube, Zagat, Waze
Website google.com
References: [5]

Google Inc. is an American multinational corporation specializing in Internet-related services and products. These include searchcloud computingsoftware and online advertising technologies.[6] Most of its profits are derived from AdWords.[7][8]

Google was founded by Larry Page and Sergey Brin while they were Ph.D. students atStanford University. Together they own about 16 percent of its shares. They incorporated Google as a privately held company on September 4, 1998. An initial public offeringfollowed on August 19, 2004. Its mission statement from the outset was “to organize the world’s information and make it universally accessible and useful”,[9] and its unofficial slogan was “Don’t be evil“.[10][11] In 2006 Google moved to headquarters in Mountain View, California, nicknamed the Googleplex.

Rapid growth since incorporation has triggered a chain of products, acquisitions, and partnerships beyond Google’s core search engine. It offers online productivity softwareincluding email, an office suite, and social networkingDesktop products include applications for web browsing, organizing and editing photos, and instant messaging. The company leads the development of the Android mobile operating system and the browser-only Google Chrome OS[12] for a specialized type of netbook known as a Chromebook. Google has moved increasingly into communications hardware: it partners with major electronics manufacturers in production of its high-end Nexus devices and acquiredMotorola Mobility in May 2012.[13] In 2012, a fiber-optic infrastructure was installed inKansas City to facilitate a Google Fiber broadband service.[14]

The corporation has been estimated to run more than one million servers in data centers around the world[15] and to process over one billion search requests[16] and about twenty-four petabytes of user-generated data each day.[17][18][19][20] In December 2012 Alexalisted google.com as the most visited website in the world. Numerous Google sites in other languages figure in the top one hundred, as do several other Google-owned sites such as YouTube and Blogger.[21] Its market dominance has led to criticism over issues including copyrightcensorship, and privacy.[22][23]


Main article: History of Google
Google's homepage in 1998

Google’s original homepage had a simple design, since its founders were not experienced inHTML, the markup language for designing web pages.[24]

Google began in January 1996 as a research project by Larry Page and Sergey Brinwhen they were both PhD students at Stanford University in Stanford, California.[25]

While conventional search engines ranked results by counting how many times the search terms appeared on the page, the two theorized about a better system that analyzed the relationships between websites.[26] They called this new technologyPageRank; it determined a website’s relevance by the number of pages, and the importance of those pages, that linked back to the original site.[27][28]

A small search engine called “RankDex” from IDD Information Services designed byRobin Li was, since 1996, already exploring a similar strategy for site-scoring and page ranking.[29] The technology in RankDex would be patented[30] and used later when Li founded Baidu in China.[31][32]

Page and Brin originally nicknamed their new search engine “BackRub”, because the system checked backlinks to estimate the importance of a site.[33][34][35] Eventually, they changed the name to Google, originating from a misspelling of the word “googol“,[36][37] the number one followed by one hundred zeros, which was picked to signify that the search engine was intended to provide large quantities of information.[38] Originally, Google ran under Stanford University’s website, with the domains google.stanford.edu and z.stanford.edu.[39][40]

The domain name for Google was registered on September 15, 1997,[41] and the company was incorporated on September 4, 1998. It was based in a friend’s (Susan Wojcicki[25]) garage in Menlo Park, California. Craig Silverstein, a fellow PhD student at Stanford, was hired as the first employee.[25][42][43]

In May 2011, the number of monthly unique visitors to Google surpassed one billion for the first time, an 8.4 percent increase from May 2010 (931 million).[44] In January 2013, Google announced it had earned $50 billion in annual revenue for the year of 2012. This marked the first time the company had reached this feat, topping their 2011 total of $38 billion.[45]

Financing and initial public offering

Google's first servers, showing lots of exposed wiring and circuit boards

Google’s first production server. Google’s production servers continue to be built with inexpensive hardware.[46]

The first funding for Google was an August 1998 contribution of US$100,000 from Andy Bechtolsheim, co-founder of Sun Microsystems, given before Google was even incorporated.[47] Early in 1999, while graduate students, Brin and Page decided that the search engine they had developed was taking up too much of their time from academic pursuits. They went to Excite CEO George Bell and offered to sell it to him for $1 million. He rejected the offer and later criticized Vinod Khosla, one of Excite’s venture capitalists, after he negotiated Brin and Page down to $750,000. On June 7, 1999, a $25 million round of funding was announced,[48] with major investors including the venture capitalfirms Kleiner Perkins Caufield & Byers and Sequoia Capital.[47]

Google’s initial public offering (IPO) took place five years later on August 19, 2004. At that time Larry Page, Sergey Brin, and Eric Schmidt agreed to work together at Google for 20 years, until the year 2024.[49] The company offered 19,605,052 shares at a price of $85 per share.[50][51] Shares were sold in a unique online auction format using a system built by Morgan Stanley and Credit Suisse, underwriters for the deal.[52][53] The sale of $1.67 billion gave Google a market capitalization of more than $23 billion.[54] The vast majority of the 271 million shares remained under the control of Google, and many Google employees became instant paper millionaires. Yahoo!, a competitor of Google, also benefited because it owned 8.4 million shares of Google before the IPO took place.[55]

Some people speculated that Google’s IPO would inevitably lead to changes in company culture. Reasons ranged from shareholder pressure for employee benefit reductions to the fact that many company executives would become instant paper millionaires.[56] As a reply to this concern, co-founders Sergey Brin and Larry Page promised in a report to potential investors that the IPO would not change the company’s culture.[57] In 2005, however, articles in The New York Times and other sources began suggesting that Google had lost its anti-corporate, no evil philosophy.[58][59][60] In an effort to maintain the company’s unique culture, Google designated a Chief Culture Officer, who also serves as the Director of Human Resources. The purpose of the Chief Culture Officer is to develop and maintain the culture and work on ways to keep true to the core values that the company was founded on: a flat organization with a collaborative environment.[61] Google has also faced allegations of sexism and ageism from former employees.[62][63]

The stock performed well after the IPO, with shares hitting $700 for the first time on October 31, 2007,[64] primarily because of strong sales and earnings in the online advertising market.[65] The surge in stock price was fueled mainly by individual investors, as opposed to large institutional investors and mutual funds.[65] The company is listed on the NASDAQ stock exchange under the ticker symbolGOOG and on the Frankfurt Stock Exchange under the ticker symbol GGQ1.


In March 1999, the company moved its offices to Palo Alto, California, which is home to several prominent Silicon Valley technology startups.[66] The next year, against Page and Brin’s initial opposition toward an advertising-funded search engine,[67] Google began selling advertisements associated with search keywords.[25] In order to maintain an uncluttered page design and increase speed, advertisements were solely text-based. Keywords were sold based on a combination of price bids and click-throughs, with bidding starting at five cents per click.[25]

This model of selling keyword advertising was first pioneered by Goto.com, an Idealab spin-off created by Bill Gross.[68][69] When the company changed names to Overture Services, it sued Google over alleged infringements of the company’s pay-per-click and bidding patents. Overture Services would later be bought by Yahoo! and renamed Yahoo! Search Marketing. The case was then settled out of court; Google agreed to issue shares of common stock to Yahoo! in exchange for a perpetual license.[70]

In 2001, Google received a patent for its PageRank mechanism.[71] The patent was officially assigned to Stanford University and lists Lawrence Page as the inventor. In 2003, after outgrowing two other locations, the company leased an office complex from Silicon Graphics at 1600 Amphitheatre Parkway in Mountain View, California.[72] The complex became known as the Googleplex, a play on the word googolplex, the number one followed by a googol zeroes. The Googleplex interiors were designed by Clive Wilkinson Architects. Three years later, Google bought the property from SGI for $319 million.[73] By that time, the name “Google” had found its way into everyday language, causing the verb “google” to be added to the Merriam-Webster Collegiate Dictionary and the Oxford English Dictionary, denoted as “to use the Google search engine to obtain information on the Internet.”[74][75]

Acquisitions and partnerships

Larry Page and Sergey Brin in 2003

Since 2001, Google has acquired many companies, primarily small venture capital-funded firms. In 2004, Google acquired Keyhole, Inc.[76] The start-up company developed a product called Earth Viewer that gave a three-dimensional view of the Earth. Google renamed the service to Google Earth in 2005. In October 2006, Google announced that it had acquired the video-sharing site YouTube for US$1.65 billion in Google stock, and the deal was finalized on November 13, 2006.[77] Google does not provide detailed figures for YouTube’s running costs, and YouTube’s revenues in 2007 were noted as “not material” in a regulatory filing.[78]In June 2008, a Forbes magazine article projected the 2008 YouTube revenue at US$200 million, noting progress in advertising sales.[79]

On April 13, 2007, Google reached an agreement to acquire DoubleClick for $3.1 billion, giving Google valuable relationships that DoubleClick had with Web publishers and advertising agencies.[80] Later that same year, Google purchased GrandCentral for $50 million.[81] The site would later be changed over to Google Voice. On August 5, 2009, Google bought out its first public company, purchasing video software maker On2 Technologies for $106.5 million.[82] Google also acquired Aardvark, a social network search engine, for $50 million, and commented on its internal blog, “we’re looking forward to collaborating to see where we can take it”.[83] In April 2010, Google announced it had acquired a hardware startup, Agnilux.[84]

In addition to the many companies Google has purchased, the company has partnered with other organizations for research, advertising, and other activities. In 2005, Google partnered with NASA Ames Research Center to build 1,000,000 square feet (93,000 m2) of offices.[85] The offices would be used for research projects involving large-scale data management, nanotechnology,distributed computing, and the entrepreneurial space industry. Google entered into a partnership with Sun Microsystems in October 2005 to help share and distribute each other’s technologies.[86]

The company also partnered with AOL[87] to enhance each other’s video search services. Google’s 2005 partnerships also included financing the new .mobi top-level domain for mobile devices, along with other companies including MicrosoftNokia, and Ericsson.[88]Google would later launch “AdSense for Mobile“, taking advantage of the emerging mobile advertising market.[89] Increasing its advertising reach even further, Google and Fox Interactive Media of News Corporation entered into a $900 million agreement to provide search and advertising on the then-popular social networking site MySpace.[90]

In 2007, Google began sponsoring NORAD Tracks Santa, displacing former sponsor AOL. NORAD Tracks Santa purports to follow Santa Claus’ progress on Christmas Eve,[91] using Google Earth to “track Santa” in 3-D for the first time.[92] Google-owned YouTube gave NORAD Tracks Santa its own channel.[93]

In 2008, Google developed a partnership with GeoEye to launch a satellite providing Google with high-resolution (0.41 m monochrome, 1.65 m color) imagery for Google Earth. The satellite was launched from Vandenberg Air Force Base on September 6, 2008.[94] Google also announced in 2008 that it was hosting an archive of Life Magazine‘s photographs. Some of the images in the archive were never published in the magazine.[95] The photos were watermarked and originally had copyright notices posted on all photos, regardless ofpublic domain status.[96]

In 2010, Google Energy made its first investment in a renewable energy project, putting $38.8 million into two wind farms in North Dakota. The company announced the two locations will generate 169.5 megawatts of power, enough to supply 55,000 homes. The farms, which were developed by NextEra Energy Resources, will reduce fossil fuel use in the region and return profits. NextEra Energy Resources sold Google a twenty-percent stake in the project to get funding for its development.[97] Also in 2010, Google purchasedGlobal IP Solutions, a Norway-based company that provides web-based teleconferencing and other related services. This acquisition enabled Google to add telephone-style services to its list of products.[98] On May 27, 2010, Google announced it had also closed the acquisition of the mobile ad network AdMob. This occurred days after the Federal Trade Commission closed its investigation into the purchase.[99] Google acquired the company for an undisclosed amount.[100] In July 2010, Google signed an agreement with an Iowa wind farm to buy 114 megawatts of energy for 20 years.[101]

On April 4, 2011, The Globe and Mail reported that Google bid $900 million for six thousand Nortel Networks patents.[102]

On August 15, 2011, Google made its largest-ever acquisition to-date when announced that it would acquire Motorola Mobility for $12.5 billion[103][104] subject to approval from regulators in the United States and Europe. In a post on Google’s blog, Google Chief Executive and co-founder Larry Page revealed that the acquisition was a strategic move to strengthen Google’s patent portfolio. The company’s Android operating system has come under fire in an industry-wide patent battle, as Apple and Microsoft have sued Android device makers such as HTC, Samsung, and Motorola.[105] The merger was completed on the May 22, 2012, after the approval ofPeople’s Republic of China.[106]

This purchase was made in part to help Google gain Motorola’s considerable patent portfolio on mobile phones and wireless technologies to help protect it in its ongoing patent disputes with other companies,[107] mainly Apple and Microsoft[105] and to allow it to continue to freely offer Android.[108] After the acquisition closed, Google began to restructure the Motorola business to fit Google’s strategy. On August 13, 2012, Google announced plans to layoff 4000 Motorola Mobility employees.[109] On December 10, 2012, Google sold the manufacturing operations of Motorola Mobility to Flextronics for $75 million.[110] As a part of the agreement, Flextronics will manufacture undisclosed Android and other mobile devices.[111] On December 19, 2012, Google sold the Motorola Home business division of Motorola Mobility to Arris Group for $2.35 billion in a cash-and-stock transaction. As a part of this deal, Google acquired a 15.7% stake in Arris Group valued at $300 million.[112]

On June 5, 2012, Google announced it acquired Quickoffice, a company widely known for their mobile productivity suite for both iOS and Android. Google plans to integrate Quickoffice’s technology into its own product suite.[113]

On February 6, 2013, Google announced it has acquired Channel Intelligence for $125 million. Channel Intelligence, a technology company that helps customers buy products online, is active globally in 31 different countries and works with over 850 retailers. Google will use this technology to enhance its e-commerce business.[114]

Google data centers

As of 2011, Google Inc. owned and operated six data centers across the U.S., plus one in Finland and another in Belgium. On September 28, 2011, the company announced plans to build three data centers at a cost of more than $200 million in Asia (Singapore, Hong Kong and Taiwan) and purchased the land for them. Google said they will be operational within two years.[115][116]

Products and services


For the 2006 fiscal year, the company reported $10.492 billion in total advertising revenues and only $112 million in licensing and other revenues.[117] In 2011, 96% of Google’s revenue was derived from its advertising programs.[118] Google has implemented various innovations in the online advertising market that helped make it one of the biggest brokers in the market. Using technology from the company DoubleClick, Google can determine user interests and target advertisements so they are relevant to their context and the user that is viewing them.[119][120]

Google Analytics allows website owners to track where and how people use their website, for example by examining click rates for all the links on a page.[121] Google advertisements can be placed on third-party websites in a two-part program. Google’s AdWords allows advertisers to display their advertisements in the Google content network, through either a cost-per-click or cost-per-view scheme. The sister service, Google AdSense, allows website owners to display these advertisements on their website and earn money every time ads are clicked.[122]

One of the disadvantages and criticisms of this program is Google’s inability to combat click fraud, when a person or automated script “clicks” on advertisements without being interested in the product, causing that advertiser to pay money to Google unduly. Industry reports in 2006 claim that approximately 14 to 20 percent of clicks were fraudulent or invalid.[123] Furthermore, there has been controversy over Google’s “search within a search”, where a secondary search box enables the user to find what they are looking for within a particular website. It was soon reported that when performing a search within a search for a specific company, advertisements from competing and rival companies often showed up along with those results, drawing users away from the site they were originally searching.[124]

Another complaint against Google’s advertising is its censorship of advertisers, though many cases concern compliance with the Digital Millennium Copyright Act. For example, in February 2003, Google stopped showing the advertisements of Oceana, a non-profit organization protesting a major cruise ship’s sewage treatment practices. Google cited its editorial policy at the time, stating “Google does not accept advertising if the ad or site advocates against other individuals, groups, or organizations.”[125] The policy was later changed.[126] In June 2008, Google reached an advertising agreement with Yahoo!, which would have allowed Yahoo! to feature Google advertisements on its web pages. The alliance between the two companies was never completely realized because of antitrustconcerns by the U.S. Department of Justice. As a result, Google pulled out of the deal in November 2008.[127][128]

In an attempt to advertise its own products, Google launched a website called Demo Slam, developed to demonstrate technology demos of Google Products.[129] Each week, two teams compete at putting Google’s technology into new contexts. Search Engine Journal said Demo Slam is “a place where creative and tech-savvy people can create videos to help the rest of the world understand all the newest and greatest technology out there.”[130]

On June 2013, Google announced the launch of Product Listing Ads in India.[131] The new ad format will show relevant information on brands, images and prices of the products that a user will be searching on the Google. Basically it will help web users to know about a product before buying it online or offline.

Search engine

Main article: Google Search

On February 14, 2012, Google updated its homepage with a minor twist. There are no red lines above the options in the black bar, and there is a tab space before the “+You”. The sign-in button has also changed, it is no longer in the black bar, instead under it as a button.

Google Search, a web search engine, is the company’s most popular service. According to market research published by comScore in November 2009, Google is the dominant search engine in the United States market, with a market share of 65.6%.[132] Google indexes billions[133] of web pages, so that users can search for the information they desire through the use of keywords and operators.

Despite its popularity, it has received criticism from a number of organizations. In 2003,The New York Times complained about Google’s indexing, claiming that Google’scaching of content on its site infringed its copyright for the content.[134] In this case, the United States District Court of Nevada ruled in favor of Google in Field v. Googleand Parker v. Google.[135][136] Furthermore, the publication 2600: The Hacker Quarterlyhas compiled a list of words that the web giant’s new instant search feature will not search.[137]

Google Watch has also criticized Google’s PageRank algorithms, saying that they discriminate against new websites and favor established sites.[138] The site has also alleged that there are connections between Google and the National Security Agency (NSA) and the Central Intelligence Agency (CIA).[139] Despite criticism, the basic search engine has spread to specific services as well, including an image search engine, the Google News search site, Google Maps, and more. In early 2006, the company launched Google Video, which allowed users to upload, search, and watch videos from the Internet.[140]

In 2009, uploads to Google Video were discontinued so that Google could focus more on the search aspect of the service.[141] The company developed Google Desktop, a desktop search application used to search for files local to one’s computer, but discontinued it in 2011. Google’s most recent development in search is its partnership with the United States Patent and Trademark Office to create Google Patents, which enables free access to information about patents and trademarks.

One of the more controversial search services Google hosts is Google Books. The company began scanning books and uploading limited previews, and full books where allowed, into its new book search engine. The Authors Guild, a group that represents 8,000 U.S. authors, filed a class action suit in a New York City federal court against Google in 2005 over this service. Google replied that it is in compliance with all existing and historical applications of copyright laws regarding books.[142] Google eventually reached a revised settlement in 2009 to limit its scans to books from the U.S., the UK, Australia, and Canada.[143] Furthermore, the Paris Civil Court ruled against Google in late 2009, asking it to remove the works of La Martinière (Éditions du Seuil) from its database.[144] In competition withAmazon.com, Google sells digital versions of new books.[145]

On July 21, 2010, in response to newcomer Bing, Google updated its image search to display a streaming sequence of thumbnails that enlarge when pointed at. Though web searches still appear in a batch per page format, on July 23, 2010, dictionary definitions for certain English words began appearing above the linked results for web searches.[146] Google’s algorithm was changed in March 2011, giving more weight to high-quality content[147] possibly by the use of n-grams to remove spun content.[148]

During the Google I/O conference in May 2013, Google’s Amit Singhal presented on the future of search, explaining that a search engine’s three primary functions will need to evolve and that search will need to: 1. Answer, 2. Converse, and 3. Anticipate. As part of his keynote talk, Singhal stated, “A computer you can talk to? And it will answer everything you ask it? Little did I know, I would grow up to become the person responsible for building my dream for the entire world.” Conversational search technology was then featured and Singhal introduced the term “hot-wording” to describe search without the need for an interface, whereby the user simply prompts the Google search engine by stating, “Ok Google.” The I/O audience was then shown a demonstration in which a user asked a question and the search engine answered back in “conversation,” in addition to the presentation of results for the query.[149]

Productivity tools

In addition to its standard web search services, Google has released a number of online productivity tools. Gmail, a free webmail service provided by Google, was launched as an invitation-only beta program on April 1, 2004,[150] and became available to the general public on February 7, 2007.[151] The service was upgraded from beta status on July 7, 2009,[152] at which time it had 146 million users monthly.[153] The service was the first online email service with one gigabyte of storage. It was also the first to keep emails from the same conversation together in one thread, similar to an Internet forum.[150] The service offers over 7600 MB of free storage with additional storage ranging from 20 GB to 16 TB available for US$0.25 per 1 GB per year.[154]

Furthermore, software developers know Gmail for its pioneering use of AJAX, a programming technique that allows web pages to be interactive without refreshing the browser.[155] One criticism of Gmail has been the potential for data disclosure, a risk associated with many online web applications. Steve Ballmer (Microsoft’s CEO),[156] Liz Figueroa,[157] Mark Rasch,[158] and the editors of Google Watch[159] believe the processing of email message content goes beyond proper use, but Google claims that mail sent to or from Gmail is never read by a human being beyond the account holder and is only used to improve relevance of advertisements.[160]

Google Docs, another part of Google’s productivity suite, allows users to create, edit, and collaborate on documents in an online environment, similar to Microsoft Word. The service was originally called Writely, but was obtained by Google on March 9, 2006, and was released as an invitation-only preview.[161] On June 6 after the acquisition, Google created an experimental spreadsheet editing program,[162] which was combined with Google Docs on October 10.[163] A program to edit presentations completed the set on September 17, 2007,[164] before all three services were taken out of beta along with Gmail, Google Calendar, and all products from the Google Apps Suite on July 7, 2009.[152]

Enterprise products

Google's search appliance

Google’s search appliance at the 2008 RSA Conference

Google entered the enterprise market in February 2002 with the launch of its Google Search Appliance, targeted toward providing search technology for larger organizations.[25] Google launched the Mini three years later, which was targeted at smaller organizations. Late in 2006, Google began to sell Custom Search Business Edition, providing customers with an advertising-free window into Google.com’s index. The service was renamed Google Site Search in 2008.[165]

Google Apps is another primary Google enterprise service offering. The service allows organizations to bring Google’s web application offerings, such as Gmail and Google Docs, into their own domains. The service is available in several editions: a basic free edition (formerly known as Google Apps Standard edition), Google Apps for Business, Google Apps for Education, and Google Apps for Government. Special editions include extras such as more disk space, API access, a service level agreement (SLA), premium support, and additional apps. In the same year Google Apps was launched, Google acquired Postini[166] and proceeded to integrate the company’s security technologies into Google Apps[167] under the name Google Postini Services.[168]

Additional Google enterprise offerings include geospatial solutions (e.g., Google Earth and Google Maps); security and archival solutions (e.g., Postini); and Chromebooks for business and education (i.e., personal computing run on browser-centric operating systems).

Other products

Nexus 4, the latest “Google phone“.

Google Translate is a server-side machine translation service, which can translate between 35 different languages. Browser extensions allow for easy access to Google Translate from the browser. The software uses corpus linguistics techniques, where the program “learns” from professionally translated documents, specifically UN and European Parliament proceedings.[169]Furthermore, a “suggest a better translation” feature accompanies the translated text, allowing users to indicate where the current translation is incorrect or otherwise inferior to another translation.

Google launched its Google News service in 2002. The company announced the creation of a “highly unusual” site that “offers a news service compiled solely by computer algorithms without human intervention. Google employs no editors, managing editors, or executive editors.”[170]The site hosts less licensed news content than Yahoo! News. Instead, it presents topically selected links to news and opinion pieces along with reproductions of their headlines, story leads, and photographs.[171] The photographs are typically reduced to thumbnail size and placed next to headlines from other news sources on the same topic to minimize copyright infringement claims. Nevertheless, Agence France Presse (AFP) sued Google for copyright infringement in federal court in the District of Columbia, a case which Google settled for an undisclosed amount in a pact that included a license of the full text of AFP articles for use on Google News.[172]

In 2006, Google made a bid to offer free wireless broadband access throughout the city of San Francisco along with Internet service provider EarthLink. Large telecommunications companies such as Comcast and Verizon opposed such efforts, claiming it was “unfair competition” and that cities would be violating their commitments to offer local monopolies to these companies. In his testimony before Congress on network neutrality in 2006, Google’s Chief Internet EvangelistVint Cerf blamed such tactics on the fact that nearly half of all consumers lack meaningful choice in broadband providers.[173] Google currently offers free wi-fi access in its hometown of Mountain View, California.[174]

In 2010, Google announced the Google Fiber project with plans to build an ultra-high-speed broadband network for 50,000 to 500,000 customers in one or more American cities.[175] On March 30, 2011, Google announced that Kansas City, Kansas would be the first community where the new network would be deployed.[176] In July 2012, Google completed the construction of a fiber-optic broadband internet network infrastructure in Kansas City, and after building an infrastructure, Google announced pricing for Google Fiber. The service will offer three options including a free broadband internet option, a 1Gbit/s internet option for $70 per month, and a version that includes television service for $120 per month.[14]

In 2007, reports surfaced that Google was planning the release of its own mobile phone, possibly a competitor to Apple‘siPhone.[177][178][179] The project, called Android, turned out not to be a phone but an operating system for mobile devices, which Google acquired and then released as an open source project under the Apache 2.0 license.[180] Google provides a software development kit for developers so applications can be created to be run on Android-based phones. In September 2008, T-Mobile released the G1, the first Android-based phone.[181] On January 5, 2010, Google released an Android phone under its own company name called the Nexus One.[182] A report in July 2013 stated that Google’s share of the global smartphone market, led by Samsung products, was 64% in March 2013.[183]

Other projects Google has worked on include a new collaborative communication service, a web browser, and a mobile operating system. The first of these was first announced on May 27, 2009. The company described Google Wave as a product that helps users communicate and collaborate on the web. The service is Google’s “email redesigned”, with realtime editing, the ability to embed audio, video, and other media, and extensions that further enhance the communication experience. Google Wave was initially in a developer’s preview, where interested users had to be invited to test the service, but was released to the general public on May 19, 2010, at Google’s I/O keynote. On September 1, 2008, Google pre-announced the upcoming availability of Google Chrome, an open source web browser,[184] which was then released on September 2, 2008. On July 7, 2009, Google announced Google Chrome OS, an open sourceLinux-based operating system that includes only a web browser and is designed to log users into their Google account.[185][186]

Google Goggles is a mobile application available on Android and iOS used for image recognition and non-text-based search. In addition to scanning QR codes, the app can recognize historic landmarks, import business cards, and solve Sudoku puzzles.[187] While Goggles could originally identify people as well, Google has limited that functionality as a privacy protection.[188]

In 2011, Google announced Google Wallet, a mobile application for wireless payments.[189] In late June 2011, Google soft-launched asocial networking service called Google+.[190] On July 14, 2011, Google announced that Google+ had reached 10 million users just two weeks after it was launched in this “limited” trial phase.[191] After four weeks in operation, it reached 25 million users.[192]

Moto X

Speaking at the D11 conference in Palos Verdes, U.S. in late May 2013, Motorola CEO Dennis Woodside—a former Google employee—announced that a new mobile device will be built by his company, which is wholly owned by Google, at a 500,000 square-feet facility in Texas, U.S. formerly used by the Nokia company. The facility will employ 2,000 people by August of 2013 and the new phone, named the “Moto X”, will be available to the public in October 2013.[193] The Moto X will feature Google Now software, and an array of sensors and two microprocessors that will mean that users can “interact with [the phone] in very different ways than you can with other devices,” in the words of Woodside. Media reports suggest that the phone will be able to activate functions preemptively based on an “awareness” of what the user is doing at any given moment.[194]

On July 3, 2013, Motorola released a full-page color advertisement in many prominent newspapers across the United States. The advertisement claimed that Motorola’s next flagship phone will be “the first smartphone designed, engineered, and assembled in the United States.”[195] On the same day that the advertisement was published, ABC News reported that customers will be able to choose the color of the phone, as well as add custom engravings and wallpaper at the time of purchase.[196]

In early July 2013, the Wall Street Journal reported that Motorola will spend nearly US$500 million on global advertising and marketing for the device. The amount is equivalent to 50% of Apple’s total advertising budget in 2012.[197]

Corporate affairs and culture

Eric Schmidt, Sergey Brin, and Larry Page sitting together

Then-CEO, now Chairman of Google Eric Schmidt with Sergey Brin and Larry Page(left to right) in 2008.

Google is known for having an informal corporate culture. On Fortune magazine’s list of best companies to work for, Google ranked first in 2007, 2008 and 2012[198][199][200] and fourth in 2009 and 2010.[201][202] Google was also nominated in 2010 to be the world’s most attractive employer to graduating students in the Universum Communications talent attraction index.[203] Google’s corporate philosophy includes principles such as “you can make money without doing evil,” “you can be serious without a suit,” and “work should be challenging and the challenge should be fun.”[204]


Google’s stock performance following its initial public offering has enabled many early employees to be competitively compensated.[205] After the company’s IPO, founders Sergey Brin and Larry Page and CEO Eric Schmidt requested that their base salary be cut to $1. Subsequent offers by the company to increase their salaries have been turned down, primarily because their main compensation continues to come from owning stock in Google. Before 2004, Schmidt made $250,000 per year, and Page and Brin each received an annual salary of $150,000.[206]

In 2007 and early 2008, several top executives left Google. In October 2007, former chief financial officer of YouTube Gideon Yu joined Facebook[207] along with Benjamin Ling, a high-ranking engineer.[208] In March 2008, Sheryl Sandberg, then vice-president of global online sales and operations, began her position as chief operating officer of Facebook.[209] At the same time, Ash ElDifrawi, formerly head of brand advertising, left to become chief marketing officer of Netshops.[210] On April 4, 2011, Larry Page became CEO and Eric Schmidt became Executive Chairman of Google.[211] In July 2012, Google’s first female employee, Marissa Mayer, left Google to become Yahoo!‘s CEO.[212]

Asian man in his twenties wearing a blue, green, yellow and red propeller hat that says "Noogle"

New employees are called “Nooglers,” and are given apropeller beanie cap to wear on their first Friday.[213]

As a motivation technique, Google uses a policy often called Innovation Time Off, where Google engineers are encouraged to spend 20% of their work time on projects that interest them. Some of Google’s newer services, such as Gmail, Google News, Orkut, and AdSense originated from these independent endeavors.[214] In a talk at Stanford University, Marissa Mayer, Google’s Vice President of Search Products and User Experience until July 2012, showed that half of all new product launches at the time had originated from the Innovation Time Off.[215]

In March 2011, consulting firm Universum announced that Google ranks first on the list of ideal employers by nearly 25 percent chosen from more than 10,000 young professionals asked.[216]Fortune magazine ranked Google as number one on its 100 Best Companies To Work For list for 2012.[217]


Main article: Googleplex
The Googleplex

The Googleplex, Google’s original and largest corporate campus

Google Mountain View campus garden

Google Mountain View dinosaur ‘Stan’

Bicycles painted in the corporate color scheme are available for free use by any employee travelling around the Googleplex

Google’s headquarters in Mountain View, California, is referred to as “the Googleplex“, a play on words on the number googolplex and the headquarters itself being a complex of buildings. The lobby is decorated with a piano, lava lamps, old server clusters, and a projection of search queries on the wall. The hallways are full of exercise balls and bicycles. Each employee has access to the corporate recreation center. Recreational amenities are scattered throughout the campus and include a workout room with weights and rowing machines, locker rooms, washers and dryers, a massage room, assorted video games, table football, a baby grand piano, a billiard table, and ping pong. In addition to the recreation room, there are snack rooms stocked with various foods and drinks, with special emphasis placed on nutrition.[218] Free food is available to employees 24/7, with paid vending machines prorated favoring nutritional value.[219]

In 2006, Google moved into 311,000 square feet (28,900 m2) of office space in New York City, at 111 Eighth Avenue in Manhattan.[220] The office was specially designed and built for Google and houses its largest advertising sales team, which has been instrumental in securing large partnerships.[220] In 2003, the company added an engineering staff in New York City, which has been responsible for more than 100 engineering projects, includingGoogle MapsGoogle Spreadsheets, and others. It is estimated that the building costs Google $10 million per year to rent and is similar in design and functionality to its Mountain View headquarters, including table football, air hockey, and ping-pong tables, and a video game area. In November 2006, Google opened offices on Carnegie Mellon‘s campus inPittsburgh, focusing on shopping-related advertisement coding and smartphone applicationsand programs.[221][222]

By late 2006, Google also established a new headquarters for its AdWords division in Ann Arbor, Michigan.[223] Other office locations in the U.S. include Ann Arbor, MichiganAtlanta, GeorgiaAustin, TexasBoulder, ColoradoCambridge, Massachusetts; New York City; San FranciscoCaliforniaSeattle, WashingtonReston, Virginia, and Washington, D.C.Furthermore, Google has several international offices.

Google's NYC office building

Google’s NYC office building houses its largest advertising sales team.[220]

Google attempts to ensure that its operations are environmentally sound. In October 2006, the company announced plans to install thousands of solar panels to provide up to 1.6 megawatts of electricity, enough to satisfy approximately 30% of the campus’ energy needs.[224] The system will be the largest solar power system constructed on a U.S. corporate campus and one of the largest on any corporate site in the world.[224] In addition, Google announced in 2009 that it was deploying herds of goats to keep grassland around the Googleplex short, helping to prevent the threat from seasonal bush fires while also reducing the carbon footprint of mowing the extensive grounds.[225][226]

The idea of trimming lawns using goats originated from R. J. Widlar, an engineer who worked for National Semiconductor.[227] Google has faced accusations in Harper’s Magazine of being an “energy glutton”. The company was accused of employing its “Don’t be evil” motto and its public energy-saving campaigns to cover up or make up for the massive amounts of energy its servers require.[228]

Easter eggs and April Fools’ Day jokes

Google has a tradition of creating April Fools’ Day jokes. For example, Google MentalPlexallegedly featured the use of mental power to search the web.[229] In 2007, Google announced a free Internet service called TiSP, or Toilet Internet Service Provider, where one obtained a connection by flushing one end of a fiber-optic cable down their toilet.[230] Also in 2007, Google’s Gmail page displayed an announcement for Gmail Paper, allowing users to have email messages printed and shipped to them.[231] In 2008, Google announced Gmail Custom time where users could change the time that the email was sent.[232]

In 2010, Google jokingly changed its company name to Topeka in honor of Topeka, Kansas, whose mayor actually changed the city’s name to Google for a short amount of time in an attempt to sway Google’s decision in its new Google Fiber Project.[233][234] In 2011, Google announced Gmail Motion, an interactive way of controlling Gmail and the computer with body movements via the user’s webcam.[235]

In addition to April Fools’ Day jokes, Google’s services contain easter eggs. For instance, Google included the Swedish Chef‘s “Bork bork bork,” Pig Latin, “Hacker” or leetspeak,Elmer FuddPirate, and Klingon as language selections for its search engine.[236] In addition, the search engine calculator provides the Answer to the Ultimate Question of Life, the Universe, and Everything from Douglas Adams‘ The Hitchhiker’s Guide to the Galaxy.[237] Furthermore, when searching the word “recursion”, the spell-checker’s result for the properly spelled word is exactly the same word, creating a recursive link.[238]

Likewise, when searching for the word “anagram,” meaning a rearrangement of letters from one word to form other valid words, Google’s suggestion feature displays “Did you mean: nag a ram?”[239] In Google Maps, searching for directions between places separated by large bodies of water, such as Los Angeles and Tokyo, results in instructions to “kayak across the Pacific Ocean.” During FIFA World Cup 2010, search queries like “World Cup“, “FIFA“, etc. caused the “Goooo…gle” page indicator at the bottom of every result page to read “Goooo…al!” instead.[240] Typing ‘Do a barrel roll’ in the search engine makes the page do a 360° rotation.


Main article: Google.org

In 2004, Google formed the not-for-profit philanthropic Google.org, with a start-up fund of $1 billion.[241] The mission of the organization is to create awareness about climate change, global public health, and global poverty. One of its first projects was to develop a viableplug-in hybrid electric vehicle that can attain 100 miles per gallon. Google hired Larry Brilliant as the program’s executive director in 2004,[242] and the current director is Megan Smith.[243]

In 2008 Google announced its “project 10100” which accepted ideas for how to help the community and then allowed Google users to vote on their favorites.[244] After two years of silence, during which many wondered what had happened to the program,[245] Google revealed the winners of the project, giving a total of ten million dollars to various ideas ranging from non-profit organizations that promote education to a website that intends to make all legal documents public and online.[246]

In 2011, Google donated 1 million euros to International Mathematical Olympiad to support the next five annual International Mathematical Olympiads (2011–2015).[247] On July 2012, Google launched a “Legalize Love” campaign in support of gay rights.[248]

Tax avoidance

Google uses various tax avoidance strategies. Consequently, out of the five largest American technology companies it pays the lowest taxes to the countries of origin of its revenues. The company accomplishes this partly by licensing technology through subsidiaries inIreland, Bermuda, the Bahamas, and the Netherlands.[249] This has reportedly sparked a French investigation into Google’s transfer pricing practices.[250]

Following criticism of the amount of corporate taxes that Google paid in the United Kingdom, Chairman Eric Schmidt said, “It’s called capitalism. We are proudly capitalistic.” During the same December 2012 interview Schmidt “confirmed that the company had no intention of paying more to the UK exchequer.”[251] In 2013, Schmidt responded to questions about taxes paid in the UK by pointing to the advertising fees Google charged UK companies as a source of economic growth.[252]

VP Matt Brittin testified to the Public Accounts Committee of the UK house of commons that his UK sales team made no sales and hence owed no sales taxes to the UK.[253]

Network neutrality

Google is a noted supporter of network neutrality. According to Google’s Guide to Net Neutrality:

Network neutrality is the principle that Internet users should be in control of what content they view and what applications they use on the Internet. The Internet has operated according to this neutrality principle since its earliest days… Fundamentally, net neutrality is about equal access to the Internet. In our view, the broadband carriers should not be permitted to use their market power to discriminate against competing applications or content. Just as telephone companies are not permitted to tell consumers who they can call or what they can say, broadband carriers should not be allowed to use their market power to control activity online.[254]

On February 7, 2006, Vint Cerf, a co-inventor of the Internet Protocol (IP) and current Vice President and “Chief Internet Evangelist” at Google, testified to Congress that “allowing broadband carriers to control what people see and do online would fundamentally undermine the principles that have made the Internet such a success.”[255]


Google promotes itself as a corporation that is committed to helping the environment and, since 2007, has aimed for carbon neutrality in regard to its operations. The Google Green website states that “Google is creating a better web that’s better for the environment. We’re greening our company by using resources efficiently and supporting renewable power.” On the website, Google also claims that businesses using “Gmail decreases its environmental impact by up to 98%” and that its data centers use 50% less energy. In 2011, Google announced at its annual I/O conference that it was developing a new application plug-in to increase the efficiency of automobiles. Named “Prediction”, Google collaborated with Ford engineers on the technology that maximizes the fuel and power consumption of automobiles.[256][257]

Controversy was generated in June 2013 after the Washington Post news outlet revealed that Google had donated US$50,000 to the Competitive Enterprise Institute, a right-wing organization responsible for numerous law suits that aimed to discredit the science behind climate change.[258] Google was further criticized in July 2013 following the publicity for a Google-hosted fundraiser for Oklahoma Republican politician Jim Inhofe, who is well known for dismissing climate change science as a “hoax” in the U.S. Senate. Tickets for the event range between US$250 and US$2,500, and a portion of the funds raised will be donated to the national Republican Senatorial Committee.[259]

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about moon


From Wikipedia, the free encyclopedia
This article is about Earth’s Moon. For moons in general, see Natural satellite. For other uses, see Moon (disambiguation).
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The Moon Moon symbol
Full moon in the darkness of the night sky. It is patterned with a mix of light-tone regions and darker, irregular blotches, and scattered with varying sizes of impact craters, circles surrounded by out-thrown rays of bright ejecta.

Full moon as seen from Earth’s northern hemisphere
Adjective lunarselenic
Orbital characteristics
Perigee 363,295 km
(0.0024 AU)
Apogee 405,503 km
(0.0027 AU)
Semi-major axis 384,399 km
(0.00257 AU)[1]
Eccentricity 0.0549[1]
Orbital period 27.321582 d (27 d 7 h 43.1 min[1])
Synodic period 29.530589 d (29 d 12 h 44 min 2.9 s)
Average orbital speed 1.022 km/s
Inclination 5.145° to the ecliptic[2] (between 18.29° and 28.58° to Earth’s equator)[1]
Longitude of ascending node regressing by one revolution in 18.6 years
Argument of perigee progressing by one revolution in 8.85 years
Satellite of Earth
Physical characteristics
Mean radius 1,737.10 km  (0.273 Earths)[1][3]
Equatorialradius 1,738.14 km (0.273 Earths)[3]
Polar radius 1,735.97 km  (0.273 Earths)[3]
Flattening 0.00125
Circumference 10,921 km (equatorial)
Surface area 3.793 × 107 km2  (0.074 Earths)
Volume 2.1958 × 1010 km3  (0.020 Earths)
Mass 7.3477 × 1022 kg  (0.012300 Earths[1])
Mean density 3.3464 g/cm3[1]
Equatorial surface gravity 1.622 m/s2 (0.165 4 g)
Escape velocity 2.38 km/s
Sidereal rotation period 27.321582 d (synchronous)
Equatorial rotation velocity 4.627 m/s
Axial tilt 1.5424° (to ecliptic)
6.687° (to orbit plane)[2]
Albedo 0.136[4]
Surface temp. min mean max
equator 100 K 220 K 390 K
85°N[5] 70 K 130 K 230 K
Apparent magnitude −2.5 to −12.9[a]
−12.74 (mean full moon)[3]
Angular diameter 29.3 to 34.1 arcminutes[3][b]
Surfacepressure 10−7 Pa (day)
10−10 Pa (night)[c]
Composition ArHeNaKHRn

Hubble views of Copernicus crater (inset), which is about 58 miles (93 km) wide

Red and orange tinted Moon, as seen from Earth during a lunar eclipse, where the Earth comes between the Moon and Sun

The Moon is the only natural satellite of the Earth[d][7] and the fifth largest moon in the Solar System. It is the largest natural satellite of a planet in the Solar System relative to the size of its primary,[e] having 27% the diameter and 60% the density of Earth, resulting in 181 its mass. Among satellites with known densities, the Moon is the second densest, after Io, a satellite of Jupiter.

The Moon is unique among natural satellites in that it experiences a stronger gravitational attraction to the Sun than to its primary, the Earth. As a consequence, its path is always concave to the Sun. It can be argued that this makes the Moon a planet, orbiting the Sun, rather than a satellite of the Earth. Usually, it is considered to be in orbit around the Earth, but its orbit is substantially distorted from a simple elliptical shape by the gravity of the Sun, which includes a tidal gradient which causes the Moon to be attracted less strongly in the direction of the Earth at Full and New Moon than at the quarter phases (in a frame of reference in which the Earth is stationary). This perturbs the orbit so as to make its curvature more acute in the directions of the quarter phases than elsewhere. If the orbit were otherwise circular, this perturbation would make it approximately elliptical, with its major axis lying along the direction of the Earth’s motion around the Sun. The Earth would be at the centre of this ellipse, rather than at one of its foci. In reality, this perturbation is superimposed on the elliptical orbit of the Moon, rotating with the seasons. The Moon’s motion is therefore quite complex, and can be calculated only very approximately by assuming the orbit to be an ellipse. Likewise, the parameters of the orbit, eccentricity, semimajor axis, etc., can be stated only as approximate averages.

The Moon is in synchronous rotation with Earth, always showing the same face with its near side marked by dark volcanic maria that fill between the bright ancient crustal highlands and the prominent impact craters. It is the brightest object in the sky after the Sun, although its surface is actually very dark, with a reflectancesimilar to that of coal. Its prominence in the sky and its regular cycle of phaseshave, since ancient times, made the Moon an important cultural influence onlanguagecalendarsart and mythology. The Moon’s gravitational influence produces the ocean tides and the minute lengthening of the day. The Moon’s current orbital distance, about thirty times the diameter of the Earth, causes it to appear almost the same size in the sky as the Sun, allowing it to cover the Sun nearly precisely in total solar eclipses. This matching of apparent visual size is a coincidence. The Moon’s linear distance from the Earth is currently increasing at a rate of 3.82±0.07cm per year, but this rate is not constant.[8]

The Moon is thought to have formed nearly 4.5 billion years ago, not long after the Earth. Although there have been several hypotheses for its origin in the past, the current most widely accepted explanation is that the Moon formed from the debris left over after a giant impact between Earth and a Mars-sized body. The Moon is the only celestial body other than Earth on which humans have set foot. TheSoviet Union‘s Luna programme was the first to reach the Moon with unmannedspacecraft in 1959; the United States’ NASA Apollo program achieved the only manned missions to date, beginning with the first manned lunar orbiting mission by Apollo 8 in 1968, and six manned lunar landings between 1969 and 1972, with the first being Apollo 11. These missions returned over 380 kg of lunar rocks, which have been used to develop a geological understanding of the Moon’s origins, the formation of its internal structure, and its subsequent history.

After the Apollo 17 mission in 1972, the Moon has been visited only by unmanned spacecraft, notably by the final Soviet Lunokhod rover. Since 2004, Japan, China, India, the United States, and the European Space Agency have each sent lunar orbiters. These spacecraft have contributed to confirming the discovery of lunar water ice in permanently shadowed craters at the poles and bound into the lunarregolith. Future manned missions to the Moon have been planned, including government as well as privately funded efforts. The Moon remains, under the Outer Space Treaty, free to all nations to explore for peaceful purposes.



Name and etymology

The English proper name for Earth’s natural satellite is “the Moon”.[9][10] The nounmoon derives from moone (around 1380), which developed from mone (1135), which derives from Old English mōna (dating from before 725), which, like all Germanic language cognates, ultimately stems from Proto-Germanic *mǣnōn.[11]

The principal modern English adjective pertaining to the Moon is lunar, derived from the Latin Luna. Another less common adjective isselenic, derived from the Ancient Greek Selene (Σελήνη), from which the prefix “seleno-” (as in selenography) is derived.[12]


The evolution of the Moon and a tour of the Moon.

Several mechanisms have been proposed for the Moon’s formation 4.527 ± 0.010 billionyears ago,[f] some 30–50 million years after the origin of the Solar System.[13] These included the fission of the Moon from the Earth’s crust through centrifugal force[14](which would require too great an initial spin of the Earth),[15] the gravitational capture of a pre-formed Moon[16] (which would require an unfeasibly extended atmosphere of the Earth to dissipate the energy of the passing Moon),[15] and the co-formation of the Earth and the Moon together in the primordial accretion disk (which does not explain the depletion of metallic iron in the Moon).[15] These hypotheses also cannot account for the high angular momentum of the Earth–Moon system.[17]

The prevailing hypothesis today is that the Earth–Moon system formed as a result of agiant impact, where a Mars-sized body (named Theia) collided with the newly formedproto-Earth, blasting material into orbit around it, which accreted to form the Moon.[18] Giant impacts are thought to have been common in the early Solar System. Computer simulations modelling a giant impact are consistent with measurements of the angular momentum of the Earth–Moon system and the small size of the lunar core. These simulations also show that most of the Moon came from the impactor, not from the proto-Earth.[19] However more recent tests suggest more of the Moon coalesced from the Earth and not the impactor.[20][21][22] Meteorites show that other inner Solar System bodies such as Mars and Vesta have very different oxygen and tungsten isotopic compositions to the Earth, while the Earth and Moon have near-identical isotopic compositions. Post-impact mixing of the vaporized material between the forming Earth and Moon could have equalized their isotopic compositions,[23] although this is debated.[24]

The large amount of energy released in the giant impact event and the subsequent reaccretion of material in Earth orbit would have melted the outer shell of the Earth, forming a magma ocean.[25][26] The newly formed Moon would also have had its own lunar magma ocean; estimates for its depth range from about 500 km to the entire radius of the Moon.[25]

Despite its accuracy in explaining many lines of evidence, there are still some difficulties that are not fully explained by the giant impact hypothesis, most of them involving the Moon’s composition.

In 2001, a team at the Carnegie Institute of Washington reported the most precise measurement of the isotopic signatures of lunar rocks.[27] To their surprise, the team found that the rocks from the Apollo program carried an isotopic signature that was identical with rocks from Earth, and were different from almost all other bodies in the Solar System. Since most of the material that went into orbit to form the Moon was thought to come from Theia, this observation was unexpected. In 2007, researchers from the California Institute of Technology announced that there was less than a 1% chance that Theia and Earth had identical isotopic signatures. [28] Published in 2012, an analysis of titanium isotopes in Apollo lunar samples showed that the Moon has the same composition as the Earth,[29] whichconflicts with what is expected if the Moon formed far from Earth’s orbit or from Theia. Variations on GIH may explain this data.

Physical characteristics

Internal structure

Structure of the Moon

Chemical composition of the lunar surface regolith (derived from crustal rocks)[30]
Compound Formula Composition (wt %)
Maria Highlands
silica SiO2 45.4% 45.5%
alumina Al2O3 14.9% 24.0%
lime CaO 11.8% 15.9%
iron(II) oxide FeO 14.1% 5.9%
magnesia MgO 9.2% 7.5%
titanium dioxide TiO2 3.9% 0.6%
sodium oxide Na2O 0.6% 0.6%
Total 99.9% 100.0%

The Moon is adifferentiated body: it has ageochemically distinctcrustmantle, and core. The Moon has a solid iron-rich inner core with a radius of 240 kilometers and a fluid outer core primarily made of liquid iron with a radius of roughly 300 kilometers. Around the core is a partially molten boundary layer with a radius of about 500 kilometers.[31] This structure is thought to have developed through thefractional crystallization of a global magma ocean shortly after the Moon’s formation 4.5 billion years ago.[32] Crystallization of this magma ocean would have created a mafic mantle from the precipitation and sinking of the minerals olivineclinopyroxene, and orthopyroxene; after about three-quarters of the magma ocean had crystallised, lower-density plagioclase minerals could form and float into a crust on top.[33] The final liquids to crystallise would have been initially sandwiched between the crust and mantle, with a high abundance of incompatible and heat-producing elements.[1] Consistent with this, geochemical mapping from orbit shows the crust is mostly anorthosite,[6] and moon rock samples of the flood lavas erupted on the surface from partial melting in the mantle confirm the mafic mantle composition, which is more iron rich than that of Earth.[1]Geophysical techniques suggest that the crust is on average ~50 km thick.[1]

The Moon is the second densest satellite in the Solar System after Io.[34] However, the inner core of the Moon is small, with a radius of about 350 km or less;[1] this is only ~20% the size of the Moon, in contrast to the ~50% of most other terrestrial bodies[clarification needed]. Its composition is not well constrained, but it is probably metallic iron alloyed with a small amount of sulphurand nickel; analyses of the Moon’s time-variable rotation indicate that it is at least partly molten.[35]

Surface geology

Main articles: Geology of the Moon and Moon rocks
This full disk is nearly featureless, a uniform grey surface with almost no dark mare. There are many bright overlapping dots of impact craters.
Far side of the Moon. Note the almost complete lack of darkmaria.[36]

Topography of the Moon.

The topography of the Moon has been measured with laser altimetryand stereo image analysis.[37] The most visible topographic feature is the giant far side South Pole – Aitken basin, some 2,240 km in diameter, the largest crater on the Moon and the largest known crater in the Solar System.[38][39] At 13 km deep, its floor is the lowest elevation on the Moon.[38][40] The highest elevations are found just to its north-east, and it has been suggested that this area might have been thickened by the oblique formation impact of South Pole – Aitken.[41] Other large impact basins, such as ImbriumSerenitatis,CrisiumSmythii, and Orientale, also possess regionally low elevations and elevated rims.[38] The lunar far side is on average about 1.9 km higher than the near side.[1]

Volcanic features

Main article: Lunar mare

The dark and relatively featureless lunar plains which can clearly be seen with the naked eye are called maria (Latin for “seas”; singularmare), since they were believed by ancient astronomers to be filled with water.[42] They are now known to be vast solidified pools of ancient basaltic lava. While similar to terrestrial basalts, the mare basalts have much higher abundances of iron and are completely lacking in minerals altered by water.[43][44] The majority of these lavas erupted or flowed into the depressions associated with impact basins. Several geologic provinces containing shield volcanoes and volcanicdomes are found within the near side maria.[45]

Maria are found almost exclusively on the near side of the Moon, covering 31% of the surface on the near side,[46] compared with a few scattered patches on the far side covering only 2%.[47] This is thought to be due to a concentration of heat-producing elements under the crust on the near side, seen on geochemical maps obtained by Lunar Prospectors gamma-ray spectrometer, which would have caused the underlying mantle to heat up, partially melt, rise to the surface and erupt.[33][48][49] Most of the Moon’s mare basalts erupted during the Imbrian period, 3.0–3.5 billion years ago, although some radiometrically dated samples are as old as 4.2 billion years,[50] and the youngest eruptions, dated by crater counting, appear to have been only 1.2 billion years ago.[51]

The lighter-coloured regions of the Moon are called terrae, or more commonly highlands, since they are higher than most maria. They have been radiometrically dated as forming 4.4 billion years ago, and may represent plagioclase cumulates of the lunar magma ocean.[50][51] In contrast to the Earth, no major lunar mountains are believed to have formed as a result of tectonic events.[52]

The concentration of mare on the Near Side likely reflects the substantially thicker crust of the highlands of the Far Side, which may have formed in a slow-velocity impact of a second terran moon a few tens of millions of years after the formations of the moons themselves.[53][54]

Impact craters

A grey, many-ridged surface from high above. The largest feature is a circular ringed structure with high walled sides and a lower central peak: the entire surface out to the horizon is filled with similar structures that are smaller and overlapping.

Lunar crater Daedalus on the Moon’s far side

The other major geologic process that has affected the Moon’s surface is impact cratering,[55] with craters formed when asteroids and comets collide with the lunar surface. There are estimated to be roughly 300,000 craters wider than 1 km on the Moon’s near side alone.[56] Some of these are named for scholars, scientists, artists and explorers.[57] Thelunar geologic timescale is based on the most prominent impact events, including Nectaris,Imbrium, and Orientale, structures characterized by multiple rings of uplifted material, typically hundreds to thousands of kilometres in diameter and associated with a broad apron of ejecta deposits that form a regional stratigraphic horizon.[58] The lack of an atmosphere, weather and recent geological processes mean that many of these craters are well-preserved. While only a few multi-ring basins have been definitively dated, they are useful for assigning relative ages. Since impact craters accumulate at a nearly constant rate, counting the number of craters per unit area can be used to estimate the age of the surface.[58] The radiometric ages of impact-melted rocks collected during the Apollo missions cluster between 3.8 and 4.1 billion years old: this has been used to propose a Late Heavy Bombardment of impacts.[59]

Blanketed on top of the Moon’s crust is a highly comminuted (broken into ever smaller particles) and impact gardened surface layer called regolith, formed by impact processes. The finer regolith, the lunar soil of silicon dioxide glass, has a texture like snow and smell like spent gunpowder.[60] The regolith of older surfaces is generally thicker than for younger surfaces: it varies in thickness from 10–20 m in the highlands and 3–5 m in the maria.[61] Beneath the finely comminuted regolith layer is the megaregolith, a layer of highly fractured bedrock many kilometres thick.[62]

Presence of water

Main article: Lunar water
Twenty degrees of latitude of the Moon's disk, completely covered in the overlapping circles of craters. The illumination angles are from all directions, keeping almost all the crater floors in sunlight, but a set of merged crater floors right at the south pole are completely shadowed.

Mosaic image of the lunar south pole as taken by Clementine: note permanent polar shadow.

Liquid water cannot persist on the lunar surface. When exposed to solar radiation, water quickly decomposes through a process known as photodissociation and is lost to space. However since the 1960s, scientists have hypothesized that water ice may be deposited by impacting comets or possibly produced by the reaction of oxygen-rich lunar rocks, and hydrogen from solar wind, leaving traces of water which could possibly survive in cold, permanently shadowed craters at either pole on the Moon.[63][64] Computer simulations suggest that up to 14,000 km2 of the surface may be in permanent shadow.[65] The presence of usable quantities of water on the Moon is an important factor in rendering lunar habitation as a cost-effective plan; the alternative of transporting water from Earth would be prohibitively expensive.[66]

In years since, signatures of water have been found to exist on the lunar surface.[67] In 1994, the bistatic radar experiment located on the Clementine spacecraft, indicated the existence of small, frozen pockets of water close to the surface. However, later radar observations byArecibo, suggest these findings may rather be rocks ejected from young impact craters.[68]In 1998, the neutron spectrometer located on the Lunar Prospector spacecraft, indicated that high concentrations of hydrogen are present in the first meter of depth in the regolith near the polar regions.[69] In 2008, an analysis of volcanic lava beads, brought back to Earth aboard Apollo 15, showed small amounts of water to exist in the interior of the beads.[70]

The 2008, Chandrayaan-1 spacecraft has since confirmed the existence of surface water ice, using the on-board Moon Mineralogy Mapper. The spectrometer observed absorption lines common to hydroxyl, in reflected sunlight, providing evidence of large quantities of water ice, on the lunar surface. The spacecraft showed that concentrations may possibly be as high as 1,000 ppm.[71] In 2009,LCROSS sent a 2300 kg impactor into a permanently shadowed polar crater, and detected at least 100 kg of water in a plume of ejected material.[72][73] Another examination of the LCROSS data showed the amount of detected water, to be closer to 155 kilograms (± 12 kg).[74]

In May 2011, Erik Hauri et al. reported[75] 615–1410 ppm water in melt inclusions in lunar sample 74220, the famous high-titanium “orange glass soil” of volcanic origin collected during the Apollo 17 mission in 1972. The inclusions were formed during explosive eruptions on the Moon approximately 3.7 billion years ago. This concentration is comparable with that of magma in Earth’s upper mantle. While of considerable selenological interest, Hauri’s announcement affords little comfort to would-be lunar colonists—the sample originated many kilometers below the surface, and the inclusions are so difficult to access that it took 39 years to find them with a state-of-the-art ion microprobe instrument.

Gravitational field

Main article: Gravity of the Moon

Gravity field of the Moon

The gravitational field of the Moon has been measured through tracking the Doppler shift of radio signals emitted by orbiting spacecraft. The main lunar gravity features are mascons, large positive gravitational anomalies associated with some of the giant impact basins, partly caused by the dense mare basaltic lava flows that fill these basins.[76][77] These anomalies greatly influence the orbit of spacecraft about the Moon. There are some puzzles: lava flows by themselves cannot explain all of the gravitational signature, and some mascons exist that are not linked to mare volcanism.[78]

Magnetic field

The Moon has an external magnetic field of about 1–100 nanoteslas, less than one-hundredth that of the Earth. It does not currently have a global dipolar magnetic field, as would be generated by a liquid metal coregeodynamo, and only has crustal magnetization, probably acquired early in lunar history when a geodynamo was still operating.[79][80]Alternatively, some of the remnant magnetization may be from transient magnetic fields generated during large impact events, through the expansion of an impact-generated plasma cloud in the presence of an ambient magnetic field—this is supported by the apparent location of the largest crustal magnetizations near the antipodes of the giant impact basins.[81]


At sunrise and sunset many Apollo crews saw glows and light rays.[82]

Main article: Atmosphere of the Moon

The Moon has an atmosphere so tenuous as to be nearly vacuum, with a total mass of less than 10 metric tons.[83] The surface pressure of this small mass is around 3 × 10−15 atm(0.3 nPa); it varies with the lunar day. Its sources include outgassing and sputtering, the release of atoms from the bombardment of lunar soil by solar wind ions.[6][84] Elements that have been detected include sodium and potassium, produced by sputtering, which are also found in the atmospheres of Mercury and Iohelium-4 from the solar wind; and argon-40,radon-222, and polonium-210, outgassed after their creation by radioactive decay within the crust and mantle.[85][86] The absence of such neutral species (atoms or molecules) asoxygennitrogencarbonhydrogen and magnesium, which are present in the regolith, is not understood.[85] Water vapour has been detected by Chandrayaan-1 and found to vary with latitude, with a maximum at ~60–70 degrees; it is possibly generated from the sublimation of water ice in the regolith.[87] These gases can either return into the regolith due to the Moon’s gravity or be lost to space, either through solar radiation pressure or, if they are ionized, by being swept away by the solar wind’s magnetic field.[85]


The Moon’s north pole during summer.

The Moon’s axial tilt with respect to the ecliptic is only 1.5424°,[88] much less than the 23.44° of the Earth. Because of this, the Moon’s solar illumination varies much less with season, and topographical details play a crucial role in seasonal effects.[89] From images taken by Clementine in 1994, it appears that four mountainous regions on the rim of Peary crater at the Moon’s north pole may remain illuminated for the entire lunar day, creating peaks of eternal light. No such regions exist at the south pole. Similarly, there are places that remain in permanent shadow at the bottoms of many polar craters,[65] and these dark craters are extremely cold: Lunar Reconnaissance Orbiter measured the lowest summer temperatures in craters at the southern pole at 35 K (−238 °C)[90] and just 26 K close to the winter solstice in north polar Hermite Crater. This is the coldest temperature in the Solar System ever measured by a spacecraft, colder even than the surface of Pluto.[89]

Relationship to Earth

The Earth has a pronounced axial tilt; the Moon's orbit is not perpendicular to Earth's axis, but lies close to the Earth's orbital plane.

Schematic of the Earth–Moon system (without a consistent scale)


Main articles: Orbit of the Moon and Lunar theory

The Moon makes a complete orbit around the Earth with respect to the fixed stars about once every 27.3 days[g] (its sidereal period). However, since the Earth is moving in its orbit about the Sun at the same time, it takes slightly longer for the Moon to show the samephase to Earth, which is about 29.5 days[h] (its synodic period).[46]Unlike most satellites of other planets, the Moon orbits nearer theecliptic plane than to the planet’s equatorial plane. The Moon’s orbit is subtly perturbed by the Sun and Earth in many small, complex and interacting ways. For example, the plane of the Moon’s orbital motiongradually rotates, which affects other aspects of lunar motion. These follow-on effects are mathematically described by Cassini’s laws.[91]

Earth and Moon, showing their sizes and distance to scale. The yellow bar represents a pulse of light traveling from Earth to Moon in 1.26 seconds.

Relative size

A view of the Moon orbiting the Earth from a point above the north ecliptic pole. Objects are to scale.

The Moon is exceptionally large relative to the Earth: a quarter the diameter of the planet and 1/81 its mass.[46] It is the largest moon in the Solar System relative to the size of its planet, though Charon is larger relative to the dwarf planet Pluto, at 1/9 Pluto’s mass.[92]

However, the Earth and Moon are still considered a planet–satellite system, rather than a double-planet system, as their barycentre, the common centre of mass, is located 1,700 km (about a quarter of the Earth’s radius) beneath the surface of the Earth.[93]

Appearance from Earth

Moon setting in western sky over High Desert (California)

The Moon is in synchronous rotation: it rotates about its axis in about the same time it takes to orbit the Earth. This results in it nearly always keeping the same face turned towards the Earth. The Moon used to rotate at a faster rate, but early in its history, its rotation slowed and became tidally locked in this orientation as a result of frictional effects associated with tidal deformations caused by the Earth.[94] The side of the Moon that faces Earth is called the near side, and the opposite side the far side. The far side is often called the “dark side”, but in fact, it is illuminated as often as the near side: once per lunar day, during the new moon phase we observe on Earth when the near side is dark.[95]

The Moon has an exceptionally low albedo, giving it a similar reflectance to coal. Despite this, it is the second brightest object in the sky after the Sun.[46][i] This is partly due to the brightness enhancement of the opposition effect; at quarter phase, the Moon is only one-tenth as bright, rather than half as bright, as at full moon.[96]

Additionally, colour constancy in the visual system recalibrates the relations between the colours of an object and its surroundings, and since the surrounding sky is comparatively dark, the sunlit Moon is perceived as a bright object. The edges of the full moon seem as bright as the centre, with no limb darkening, due to the reflective properties of lunar soil, which reflects more light back towards the Sun than in other directions. The Moon does appear larger when close to the horizon, but this is a purely psychological effect, known as theMoon illusion, first described in the 7th century BC.[97] The full moon subtends an arc of about 0.52° (on average) in the sky, roughly the same apparent size as the Sun (see eclipses).

The monthly changes of angle between the direction of illumination by the Sun and viewing from Earth, and the phases of the Moon that result

The highest altitude of the Moon in the sky varies: while it has nearly the same limit as the Sun, it alters with the lunar phase and with the season of the year, with the full moon highest during winter. The 18.6-year nodes cycle also has an influence: when the ascending node of the lunar orbit is in the vernal equinox, the lunar declination can go as far as 28° each month. This means the Moon can go overhead at latitudes up to 28° from the equator, instead of only 18°. The orientation of the Moon’s crescent also depends on the latitude of the observation site: close to the equator, an observer can see a smile-shaped crescent Moon.[98]

The distance between the Moon and the Earth varies from around 356,400 km to 406,700 km at the extreme perigees (closest) and apogees (farthest). On 19 March 2011, it was closer to the Earth while at full phase than it has been since 1993.[99] Reported as a “super moon“, this closest point coincides within an hour of a full moon, and it thus appeared 30 percent brighter, and 14 percent larger in diameter than when at its greatest distance.[100][101][102]

There has been historical controversy over whether features on the Moon’s surface change over time. Today, many of these claims are thought to be illusory, resulting from observation under different lighting conditions, poor astronomical seeing, or inadequate drawings. However, outgassing does occasionally occur, and could be responsible for a minor percentage of the reported lunar transient phenomena. Recently, it has been suggested that a roughly 3 km diameter region of the lunar surface was modified by a gas release event about a million years ago.[103][104] The Moon’s appearance, like that of the Sun, can be affected by Earth’s atmosphere: common effects are a 22° halo ring formed when the Moon’s light is refracted through the ice crystals of high cirrostratus cloud, and smallercoronal rings when the Moon is seen through thin clouds.[105]

Tidal effects

The tides on the Earth are mostly generated by the gradient in intensity of the Moon’s gravitational pull from one side of the Earth to the other, the tidal forces. This forms two tidal bulges on the Earth, which are most clearly seen in elevated sea level as ocean tides.[106]Since the Earth spins about 27 times faster than the Moon moves around it, the bulges are dragged along with the Earth’s surface faster than the Moon moves, rotating around the Earth once a day as it spins on its axis.[106] The ocean tides are magnified by other effects: frictional coupling of water to Earth’s rotation through the ocean floors, the inertia of water’s movement, ocean basins that get shallower near land, and oscillations between different ocean basins.[107] The gravitational attraction of the Sun on the Earth’s oceans is almost half that of the Moon, and their gravitational interplay is responsible for spring and neap tides.[106]

Over one lunar month more than half of the Moon's surface can be seen from the surface of the Earth.

The libration of the Moon over a single lunar month.

Gravitational coupling between the Moon and the bulge nearest the Moon acts as a torqueon the Earth’s rotation, draining angular momentum and rotational kinetic energy from the Earth’s spin.[106][108] In turn, angular momentum is added to the Moon’s orbit, accelerating it, which lifts the Moon into a higher orbit with a longer period. As a result, the distance between the Earth and Moon is increasing, and the Earth’s spin slowing down.[108]Measurements from lunar ranging experiments with laser reflectors left during the Apollo missions have found that the Moon’s distance to the Earth increases by 38 mm per year[109](though this is only 0.10 ppb/year of the radius of the Moon’s orbit). Atomic clocks also show that the Earth’s day lengthens by about 15 microseconds every year,[110] slowly increasing the rate at which UTC is adjusted by leap seconds. Left to run its course, this tidal drag would continue until the spin of the Earth and the orbital period of the Moon matched. However, the Sun will become a red giant long before that, engulfing the Earth.[111][112]

The lunar surface also experiences tides of amplitude ~10 cm over 27 days, with two components: a fixed one due to the Earth, because they are in synchronous rotation, and a varying component from the Sun.[108] The Earth-induced component arises from libration, a result of the Moon’s orbital eccentricity; if the Moon’s orbit were perfectly circular, there would only be solar tides.[108] Libration also changes the angle from which the Moon is seen, allowing about 59% of its surface to be seen from the Earth (but only half at any instant).[46] The cumulative effects of stress built up by these tidal forces produces moonquakes. Moonquakes are much less common and weaker than earthquakes, although they can last for up to an hour—a significantly longer time than terrestrial earthquakes—because of the absence of water to damp out the seismic vibrations. The existence of moonquakes was an unexpected discovery from seismometers placed on the Moon by Apolloastronauts from 1969 through 1972.[113]


Main articles: Solar eclipseLunar eclipse, and Eclipse cycle
The bright disk of the Sun, showing many coronal filaments, flares and grainy patches in the wavelength of this image, is partly obscured by a small dark disk: here, the Moon covers less than a fifteenth of the Sun.
The Moon passing in front of the Sun, from the STEREO-B spacecraft.[114]
From the Earth, the Moon and Sun appear the same size. From a satellite in an Earth-trailing orbit, the Moon may appear smaller than the Sun.

Scaling the Earth down to the size of a basketball, the Moon is roughly the size of a tennis ball. The Moon’s orbit correlates closely to the 3-point shooting line of a basketball court. With the floor taken to be the ecliptic plane, the Moon’s orbit reaches a maximum height out of this plane about the length of a tennis racket. Eclipses can only occur when the Moon’s path crosses through the ecliptic so that the Sun-Moon-Earth, or Sun-Earth-Moon, are aligned.

Eclipses can only occur when the Sun, Earth, and Moon are all in a straight line (termed “syzygy“). Solar eclipses occur at new moon, when the Moon is between the Sun and Earth. In contrast, lunar eclipses occur at full moon, when the Earth is between the Sun and Moon. The apparent size of the Moon is roughly the same as that of the Sun, with both being viewed at close to one-half a degree wide. The Sun is much larger than the Moon but it is the precise vastly greater distance that coincidentally gives it the same apparent size as the much closer and much smaller Moon from the perspective of the Earth. The variations in apparent size, due to the non-circular orbits, are nearly the same as well, though occurring in different cycles. This makes possible both total (with the Moon appearing larger than the Sun) and annular(with the Moon appearing smaller than the Sun) solar eclipses.[115] In a total eclipse, the Moon completely covers the disc of the Sun and the solar coronabecomes visible to the naked eye. Since the distance between the Moon and the Earth is very slowly increasing over time,[106] the angular diameter of the Moon is decreasing. This means that hundreds of millions of years ago the Moon would always completely cover the Sun on solar eclipses, and no annular eclipses were possible. Likewise, about 600 million years from now (if the angular diameter of the Sun does not change), the Moon will no longer cover the Sun completely, and only annular eclipses will occur.[116]

Because the Moon’s orbit around the Earth is inclined by about 5° to the orbit of the Earth around the Sun, eclipses do not occur at every full and new moon. For an eclipse to occur, the Moon must be near the intersection of the two orbital planes.[116] The periodicity and recurrence of eclipses of the Sun by the Moon, and of the Moon by the Earth, is described by the saros cycle, which has a period of approximately 18 years.[117]

As the Moon is continuously blocking our view of a half-degree-wide circular area of the sky,[j][118] the related phenomenon of occultation occurs when a bright star or planet passes behind the Moon and is occulted: hidden from view. In this way, a solar eclipse is an occultation of the Sun. Because the Moon is comparatively close to the Earth, occultations of individual stars are not visible everywhere on the planet, nor at the same time. Because of the precession of the lunar orbit, each year different stars are occulted.[119]

Study and exploration

On an open folio page is a carefully drawn disk of the full moon. In the upper corners of the page are waving banners held aloft by pairs of winged cherubs. In the lower left page corner a cherub assists another to measure distances with a pair of compasses; in the lower right corner a cherub views the main map through a handheld telescope, while another, kneeling, peers at the map from over a low cloth-draped table.

Map of the Moon by Johannes Heveliusfrom his Selenographia (1647), the first map to include the libration zones.

Early studies

Understanding of the Moon’s cycles was an early development of astronomy: by the5th century BC, Babylonian astronomers had recorded the 18-year Saros cycle of lunar eclipses,[120] and Indian astronomers had described the Moon’s monthly elongation.[121] TheChinese astronomer Shi Shen (fl. 4th century BC) gave instructions for predicting solar and lunar eclipses.[122] Later, the physical form of the Moon and the cause of moonlight became understood. The ancient Greek philosopher Anaxagoras (d. 428 BC) reasoned that the Sun and Moon were both giant spherical rocks, and that the latter reflected the light of the former.[123][124] Although the Chinese of the Han Dynasty believed the Moon to be energy equated to qi, their ‘radiating influence’ theory also recognized that the light of the Moon was merely a reflection of the Sun, and Jing Fang (78–37 BC) noted the sphericity of the Moon.[125] In 2nd century AD Lucian wrote a novel where the heroes travel to the Moon, which is inhabited. In 499 AD, the Indian astronomer Aryabhata mentioned in hisAryabhatiya that reflected sunlight is the cause of the shining of the Moon.[126] The astronomer and physicist Alhazen (965–1039) found that sunlight was not reflected from the Moon like a mirror, but that light was emitted from every part of the Moon’s sunlit surface in all directions.[127] Shen Kuo (1031–1095) of the Song Dynasty created an allegory equating the waxing and waning of the Moon to a round ball of reflective silver that, when doused with white powder and viewed from the side, would appear to be a crescent.[128]

In Aristotle’s (384–322 BC) description of the universe, the Moon marked the boundary between the spheres of the mutable elements (earth, water, air and fire), and the imperishable stars of aether, an influential philosophy that would dominate for centuries.[129]However, in the 2nd century BC, Seleucus of Seleucia correctly theorized that tides were due to the attraction of the Moon, and that their height depends on the Moon’s position relative to the Sun.[130] In the same century, Aristarchus computed the size and distanceof the Moon from Earth, obtaining a value of about twenty times the Earth radius for the distance. These figures were greatly improved by Ptolemy (90–168 AD): his values of a mean distance of 59 times the Earth’s radius and a diameter of 0.292 Earth diameters were close to the correct values of about 60 and 0.273 respectively.[131] Archimedes (287–212 BC) invented a planetarium calculating motions of the Moon and the known planets.[132]

During the Middle Ages, before the invention of the telescope, the Moon was increasingly recognised as a sphere, though many believed that it was “perfectly smooth”.[133] In 1609, Galileo Galilei drew one of the first telescopic drawings of the Moon in his bookSidereus Nuncius and noted that it was not smooth but had mountains and craters. Telescopic mapping of the Moon followed: later in the 17th century, the efforts of Giovanni Battista Riccioli and Francesco Maria Grimaldi led to the system of naming of lunar features in use today. The more exact 1834–36 Mappa Selenographica of Wilhelm Beer and Johann Heinrich Mädler, and their associated 1837 book Der Mond, the first trigonometrically accurate study of lunar features, included the heights of more than a thousand mountains, and introduced the study of the Moon at accuracies possible in earthly geography.[134] Lunar craters, first noted by Galileo, were thought to be volcanic until the 1870s proposal of Richard Proctor that they were formed by collisions.[46] This view gained support in 1892 from the experimentation of geologist Grove Karl Gilbert, and from comparative studies from 1920 to the 1940s,[135] leading to the development of lunar stratigraphy, which by the 1950s was becoming a new and growing branch of astrogeology.[46]

First direct exploration: 1959–1976

Soviet missions

Main articles: Luna program and Lunokhod programme

Lunokhod 1 (lit. moonwalker), the first successful space rover.

The Cold War-inspired Space Race between the Soviet Union and the U.S. led to an acceleration of interest in exploration of the Moon. Once launchers had the necessary capabilities, these nations sent unmanned probes on both flyby and impact/lander missions. Spacecraft from the Soviet Union’s Luna program were the first to accomplish a number of goals: following three unnamed, failed missions in 1958,[136] the first man-made object to escape Earth’s gravity and pass near the Moon was Luna 1; the first man-made object to impact the lunar surface was Luna 2, and the first photographs of the normally occluded far side of the Moon were made by Luna 3, all in 1959.

The first spacecraft to perform a successful lunar soft landing was Luna 9 and the first unmanned vehicle to orbit the Moon was Luna 10, both in 1966.[46] Rock and soil sampleswere brought back to Earth by three Luna sample return missions (Luna 16 in 1970, Luna 20in 1972, and Luna 24 in 1976), which returned 0.3 kg total.[137] Two pioneering robotic roverslanded on the Moon in 1970 and 1973 as a part of Soviet Lunokhod programme.

United States missions

Main articles: Apollo program and Moon landing
The small blue-white semicircle of the Earth, almost glowing with colour in the blackness of space, rising over the limb of the desolate, cratered surface of the Moon.

Earth as viewed from Lunar orbit during the Apollo 8 mission, Christmas Eve, 1968. Africa is at the sunset terminator, both Americas are under cloud, and Antarctica is at the left end of the terminator.

Neil Armstrong and a U.S. flag

The United States launched unmanned probes to develop an understanding of the lunar surface for an eventual manned landing: the Jet Propulsion Laboratory‘s Surveyor programlanded its first spacecraft four months after Luna 9NASA‘s manned Apollo program was developed in parallel; after a series of unmanned and manned tests of the Apollo spacecraft in Earth orbit, and spurred on by a potential Soviet lunar flight, in 1968 Apollo 8 made the first crewed mission to lunar orbit. The subsequent landing of the first humans on the Moon in 1969 is seen by many as the culmination of the Space Race.[138] Neil Armstrong became the first person to walk on the Moon as the commander of the American mission Apollo 11by first setting foot on the Moon at 02:56 UTC on 21 July 1969.[139] The Apollo missions 11 to 17 (except Apollo 13, which aborted its planned lunar landing) returned 382 kg of lunar rock and soil in 2,196 separate samples.[140] The American Moon landing and return was enabled by considerable technological advances in the early 1960s, in domains such asablation chemistry, software engineering and atmospheric re-entry technology, and by highly competent management of the enormous technical undertaking.[141][142]

Scientific instrument packages were installed on the lunar surface during all the Apollo landings. Long-lived instrument stations, including heat flow probes, seismometers, andmagnetometers, were installed at the Apollo 12141516, and 17 landing sites. Direct transmission of data to Earth concluded in late 1977 due to budgetary considerations,[143][144] but as the stations’ lunar laser ranging corner-cube retroreflector arrays are passive instruments, they are still being used. Ranging to the stations is routinely performed from Earth-based stations with an accuracy of a few centimetres, and data from this experiment are being used to place constraints on the size of the lunar core.[145]

Current era: 1990–present

The dark shadowed disk of the Moon moves across the face of the quarter-phase Earth, covering only a small part of the cloud-swirled semicircle.

Earth and the Moon, as imaged by Deep Impact in September 2008 at a separation of 50 million km[146]

Post-Apollo and Luna, many more countries have become involved in direct exploration of the Moon. In 1990, Japan became the third country to place a spacecraft into lunar orbit with its Hiten spacecraft. The spacecraft released a smaller probe, Hagoromo, in lunar orbit, but the transmitter failed, preventing further scientific use of the mission.[147] In 1994, the U.S. sent the joint Defense Department/NASA spacecraft Clementine to lunar orbit. This mission obtained the first near-global topographic map of the Moon, and the first globalmultispectral images of the lunar surface.[148] This was followed in 1998 by theLunar Prospector mission, whose instruments indicated the presence of excess hydrogen at the lunar poles, which is likely to have been caused by the presence of water ice in the upper few meters of the regolith within permanently shadowed craters.[149]

The European spacecraft SMART-1, the second ion-propelled spacecraft, was in lunar orbit from 15 November 2004 until its lunar impact on 3 September 2006, and made the first detailed survey of chemical elements on the lunar surface.[150] China has expressedambitious plans for exploring the Moon, and successfully orbited its first spacecraft, Chang’e-1, from 5 November 2007 until its controlled lunar impact on 1 March 2008.[151] In its sixteen-month mission, it obtained a full image map of the Moon. Between 4 October 2007 and 10 June 2009, the Japan Aerospace Exploration Agency‘s Kaguya (Selene) mission, a lunar orbiter fitted with a high-definition video camera, and two small radio-transmitter satellites, obtained lunar geophysics data and took the first high-definition movies from beyond Earth orbit.[152][153] India’s first lunar mission, Chandrayaan I, orbited from 8 November 2008 until loss of contact on 27 August 2009, creating a high resolution chemical, mineralogical and photo-geological map of the lunar surface, and confirming the presence of water molecules in lunar soil.[154] The Indian Space Research Organisation plans to launch Chandrayaan II in 2013, which is slated to include a Russian robotic lunar rover.[155][156]

Explore what the discovery of lunar valleys tells us about the moon’s evolution.

The U.S. co-launched the Lunar Reconnaissance Orbiter (LRO) and the LCROSSimpactor and follow-up observation orbiter on 18 June 2009; LCROSS completed its mission by making a planned and widely observed impact in the crater Cabeus on 9 October 2009,[157] while LRO is currently in operation, obtaining precise lunar altimetryand high-resolution imagery. In November 2011, the LRO passed over the Aristarchus crater, which spans 40 kilometres and sinks more than 3.5 kilometres deep. The crater is one of the most visible ones from Earth. “The Aristarchus plateau is one of the most geologically diverse places on the Moon: a mysterious raised flat plateau, a giant rille carved by enormous outpourings of lava, fields of explosive volcanic ash, and all surrounded by massive flood basalts”, said Mark Robinson, principal investigator of the Lunar Reconnaissance Orbiter Camera at Arizona State University. NASA released photos of the crater on 25 December 2011.[158]

Two GRAIL spacecraft begin orbiting the Moon around 1 January 2012.[159]

Other upcoming lunar missions include Russia’s Luna-Glob: an unmanned lander, set of seismometers, and an orbiter based on its Martian Fobos-Grunt mission, which is slated to launch in 2012.[160][161] Privately funded lunar exploration has been promoted by theGoogle Lunar X Prize, announced 13 September 2007, which offers US$20 million to anyone who can land a robotic rover on the Moon and meet other specified criteria.[162] Shackleton Energy Company is building a program to establish operations on the south pole of the Moon to harvest water and supply their Propellant Depots.[163]

NASA began to plan to resume manned missions following the call by U.S. President George W. Bush on 14 January 2004 for a manned mission to the Moon by 2019 and the construction of a lunar base by 2024.[164] The Constellation program was funded and construction and testing begun on a manned spacecraft and launch vehicle,[165] and design studies for a lunar base.[166] However, that program has been cancelled in favour of a manned asteroid landing by 2025 and a manned Mars orbit by 2035.[167] India has also expressed its hope to send a manned mission to the Moon by 2020.[168]

Astronomy from the Moon

This is a picture of Earth in ultraviolet light, taken from the surface of the Moon. The day-side reflects a lot of UV light from the Sun, but the night-side shows bands of UV emission from the aurora caused by charged particles.[169]

For many years, the Moon has been recognized as an excellent site for telescopes.[170] It is relatively nearby; astronomical seeing is not a concern; certain craters near the poles are permanently dark and cold, and thus especially useful for infrared telescopes; and radio telescopes on the far side would be shielded from the radio chatter of Earth.[171] The lunar soil, although it poses a problem for any moving parts of telescopes, can be mixed withcarbon nanotubes and epoxies in the construction of mirrors up to 50 meters in diameter.[172] A lunar zenith telescope can be made cheaply with ionic liquid.[173]

In April 1972, the Apollo 16 mission recorded various astronomical photos and spectra in ultraviolet with the Far Ultraviolet Camera/Spectrograph.[174]

Legal status

Main article: Space law

Although Luna landers scattered pennants of the Soviet Union on the Moon, and U.S. flagswere symbolically planted at their landing sites by the Apollo astronauts, no nation currently claims ownership of any part of the Moon’s surface.[175] Russia and the U.S. are party to the 1967 Outer Space Treaty,[176] which defines the Moon and all outer space as the “province of all mankind“.[175] This treaty also restricts the use of the Moon to peaceful purposes, explicitly banning military installations andweapons of mass destruction.[177] The 1979 Moon Agreement was created to restrict the exploitation of the Moon’s resources by any single nation, but it has not been signed by any of the space-faring nations.[178] While several individuals have made claims to the Moon in whole or in part, none of these are considered credible.[179][180][181]

In culture

Luna, the Moon, from a 1550 edition ofGuido Bonatti‘s Liber astronomiae.

The Moon’s regular phases make it a very convenient timepiece, and the periods of its waxing and waning form the basis of many of the oldest calendars. Tally sticks, notched bones dating as far back as 20–30,000 years ago, are believed by some to mark the phases of the Moon.[182][183][184] The ~30-day month is an approximation of the lunar cycle. The English noun month and its cognates in other Germanic languages stem from Proto-Germanic *mǣnṓth-, which is connected to the above mentioned Proto-Germanic *mǣnōn, indicating the usage of a lunar calendar among the Germanic peoples (Germanic calendar) prior to the adoption of a solar calendar.[185] The same Indo-European root as moon led, viaLatin, to measure and menstrual, words which echo the Moon’s importance to many ancient cultures in measuring time (see Latin mensis and Ancient Greek μήνας (mēnas), meaning “month”).[186][187]

crescent Moon and “star” (here the planetVenus) are a common symbol of Islam, appearing in flags like:  (Turkey) (Tunisia) and  (Pakistan).

The Moon has been the subject of many works of art and literature and the inspiration for countless others. It is a motif in the visual arts, the performing arts, poetry, prose and music. A 5,000-year-old rock carving at Knowth, Ireland, may represent the Moon, which would be the earliest depiction discovered.[188] The contrast between the brighter highlands and the darker maria creates the patterns seen by different cultures as the Man in the Moon, therabbit and the buffalo, among others. In many prehistoric and ancient cultures, the Moon was personified as a deity or other supernatural phenomenon, and astrological views of the Moon continue to be propagated today.

The Moon has a long association with insanity and irrationality; the words lunacy andlunatic (popular shortening loony) are derived from the Latin name for the Moon, Luna. Philosophers Aristotle and Pliny the Elder argued that the full moon induced insanity in susceptible individuals, believing that the brain, which is mostly water, must be affected by the Moon and its power over the tides, but the Moon’s gravity is too slight to affect any single person.[189] Even today, people insist that admissions to psychiatric hospitals, traffic accidents, homicides or suicides increase during a full moon, although there is no scientific evidence to support such claims.[189]

See also

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  1. ^ The maximum value is given based on scaling of the brightness from the value of −12.74 given for an equator to Moon-centre distance of 378 000 km in the NASA factsheet reference to the minimum Earth–Moon distance given there, after the latter is corrected for the Earth’s equatorial radius of 6 378 km, giving 350 600 km. The minimum value (for a distant new moon) is based on a similar scaling using the maximum Earth–Moon distance of 407 000 km (given in the factsheet) and by calculating the brightness of the earthshine onto such a new moon. The brightness of the earthshine is [ Earth albedo × (Earth radius / Radius of Moon’s orbit)2 ] relative to the direct solar illumination that occurs for a full moon. (Earth albedo = 0.367; Earth radius = (polar radius × equatorial radius)½ = 6 367 km.)
  2. ^ The range of angular size values given are based on simple scaling of the following values given in the fact sheet reference: at an Earth-equator to Moon-centre distance of 378 000 km, the angular size is 1896 arcseconds. The same fact sheet gives extreme Earth–Moon distances of 407 000 km and 357 000 km. For the maximum angular size, the minimum distance has to be corrected for the Earth’s equatorial radius of 6 378 km, giving 350 600 km.
  3. ^ Lucey et al. (2006) give 107 particles cm−3 by day and 105 particles cm−3 by night. Along with equatorial surface temperatures of 390 Kby day and 100 K by night, the ideal gas law yields the pressures given in the infobox (rounded to the nearest order of magnitude): 10−7 Pa by day and 10−10 Pa by night.
  4. ^ There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term (Morais et al, 2002). These are quasi-satellites – they are not moons as they do not orbit the Earth. For more information, see Other moons of Earth.
  5. ^ Charon is proportionally larger in comparison to Pluto, but Pluto has been reclassified as a dwarf planet.
  6. ^ This age is calculated from isotope dating of lunar rocks.
  7. ^ More accurately, the Moon’s mean sidereal period (fixed star to fixed star) is 27.321661 days (27d 07h 43m 11.5s), and its mean tropical orbital period (from equinox to equinox) is 27.321582 days (27d 07h 43m 04.7s) (Explanatory Supplement to the Astronomical Ephemeris, 1961, at p.107).
  8. ^ More accurately, the Moon’s mean synodic period (between mean solar conjunctions) is 29.530589 days (29d 12h 44m 02.9s)(Explanatory Supplement to the Astronomical Ephemeris, 1961, at p.107).
  9. ^ The Sun’s apparent magnitude is −26.7, and the full moon’s apparent magnitude is −12.7.
  10. ^ On average, the Moon covers an area of 0.21078 square degrees on the night sky.


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San Diego

From Wikipedia, the free encyclopedia
This article is about the city in California. For the metropolitan area, see San Diego metropolitan area and San Diego County. For other uses, see San Diego (disambiguation).
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San Diego, California
—  City  —
City of San Diego

Images from top, left to right: San Diego Skyline,Coronado Bridge, museum in Balboa Park, Serra Museum in Presidio Park and the Old Point Loma lighthouse


Nickname(s): America’s Finest City
Motto: Semper Vigilans (Latin for “Ever Vigilant”)

Location of San Diego
within San Diego County

San Diego is located in United States

San Diego, California

Location in the United States

Coordinates: 32°42′54″N 117°09′45″WCoordinates32°42′54″N 117°09′45″W
Country United States
State California
County San Diego
Founded July 16, 1769
Incorporated March 27, 1850
 • Type Mayor-council
 • Body San Diego City Council
 • Mayor Bob Filner
 • City Attorney Jan Goldsmith
 • City Council members
 • City 372.398 sq mi (964.506 km2)
 • Land 325.188 sq mi (842.233 km2)
 • Water 47.210 sq mi (122.273 km2)  12.68%
Elevation sea level to 1,593 ft (sea level to 486 m)
Population (Census 2010)
 • City 1,322,553
 • Rank 1st in San Diego County
2nd in California
8th in the United States
 • Density 4,003/sq mi (1,545.4/km2)
 • Metro 3,095,313
Demonym San Diegan
Time zone PST (UTC-8)
 • Summer (DST) PDT (UTC-7)
ZIP code 92101-92117, 92119-92124, 92126-92140, 92142, 92145, 92147, 92149-92155, 92158-92172, 92174-92177, 92179, 92182, 92184, 92186, 92187, 92190-92199
Area code(s) 619858
FIPS code 66000
GNIS feature ID 1661377
Website www.sandiego.gov

San Diego /ˌsæn dˈɡ/ is a major city in California, on the coast of the Pacific Ocean in Southern California, approximately 120 miles (190 km) south of Los Angelesand immediately adjacent to the border with Mexico. San Diego is the eighth largest city in the United States and second largest in California and is one of the fastest growing cities in the nation.[2] San Diego is the birthplace of California[3] and is known for its mild year-round climate, natural deep-water harbor, extensive beaches, long association with the U.S. Navy, and recent emergence as a healthcare and biotechnology development center. The population was 1,322,553 based on latest population estimates for 2012.[4]

Historically home to the Kumeyaay people, San Diego was the first site visited by Europeans on what is now the West Coast of the United States. Upon landing in San Diego Bay in 1542, Juan Cabrillo claimed the entire area for Spain, forming the basis for the settlement of Alta California 200 years later. The Presidio and Mission of San Diego, founded in 1769, formed the first European settlement in what is now California. In 1821, San Diego became part of newly independent Mexico, and in 1850, became part of the United States following the Mexican-American War and the admission of California to the union.

The city is the county seat of San Diego County and is the economic center of the region as well as the San Diego–Tijuana metropolitan area. San Diego’s main economic engines are military and defense-related activities, tourism, international trade, and manufacturing. The presence of the University of California, San Diego(UCSD), with the affiliated UCSD Medical Center, has helped make the area a center of research in biotechnology.


Main article: History of San Diego
Historical Affiliations

Spanish Empire 1769–1821
First Mexican Empire 1821–1823
United Mexican States 1823–1848
United States 1848–present

Full length portrait of a man in his thirties wearing a long robe, woman and child visible behind him and dog to his left

Kumeyaay people lived in San Diego before Europeans settled there.

Man in his twenties or thirties standing transfixed in front of a cross his height, five onlookers

Namesake of the city, Didacus of AlcaláSaint Didacus in Ecstasy Before the Cross by Murillo (Musée des Augustins)

Oval, black and white shoulder-height portrait of a man in his forties or fifties, slightly balding wearing a suit

Namesake of Horton Plaza,Alonzo Horton developed “New Town” which became Downtown San Diego.

The original inhabitants of the region are now known as the San Dieguito and La Jolla people.[5] The area of San Diego has been inhabited for more than 10,000 years by the Kumeyaay people.[6][7] The first European to visit the region wasPortuguese-born explorer Juan Rodríguez Cabrillo sailing under the flag of Castile. Sailing his flagship San Salvador from Navidad, New Spain, Cabrillo claimed the bay for the Spanish Empire in 1542 and named the site ‘San Miguel’.[8] In November 1602, Sebastián Vizcaíno was sent to map the California coast. Arriving on his flagshipSan Diego, Vizcaíno surveyed the harbor and what are now Mission Bay and Point Loma and named the area for the Catholic Saint Didacus, a Spaniard more commonly known as San Diego de Alcalá. On November 12, 1602, the first Christian religious service of record in Alta California was conducted by Friar Antonio de la Ascensión, a member of Vizcaíno’s expedition, to celebrate the feast day of San Diego.[9]

In May 1769, Gaspar de Portolà established the Fort Presidio of San Diego on a hill near the San Diego River. In July of the same year, Mission San Diego de Alcalá was founded by Franciscan friars under Father Junípero Serra.[10] By 1797, the mission boasted the largest native population in Alta California, with over 1,400 neophytes living in and around the mission proper.[11] Mission San Diego was the southern anchor in California of the historic mission trail El Camino Real. Both the Presidio and the Mission are National Historic Landmarks.[12][13]

In 1821, Mexico won its independence from Spain, and San Diego became part of the Mexican state of Alta California. The fort on Presidio Hill was gradually abandoned, while the town of San Diego grew up on the level land below Presidio Hill. The Mission was secularized by the Mexican government, and most of the Mission lands were distributed to wealthy Californio settlers.

As a result of the Mexican-American War of 1846–1848, the territory of Alta California, including San Diego, was ceded to the United States by Mexico. The Battle of San Pasqual, a battle of the Mexican-American War, was fought in 1846 in the San Pasqual Valley which is now part of the city of San Diego. The state of California was admitted to the United States in 1850. That same year San Diego was designated the seat of the newly established San Diego County and was incorporated as a city. The initial city charter was established in 1889 and today’s city charter was adopted in 1931.[14]

The original town of San Diego was located at the foot of Presidio Hill, in the area which is now Old Town San Diego State Historic Park. The location was not ideal, being several miles away from navigable water. In the late 1860s, Alonzo Horton promoted a move to “New Town”, several miles south of the original settlement, in the area which became Downtown San Diego. People and businesses flocked to New Town because of its location on San Diego Bay convenient to shipping. New Town quickly eclipsed the original settlement, known to this day as Old Town, and became the economic and governmental heart of the city.[15]

In the early part of the 20th century, San Diego hosted two World’s Fairs: the Panama-California Exposition in 1915 and the California Pacific International Exposition in 1935. Both expositions were held in Balboa Park, and many of the Spanish/Baroque-style buildings that were built for those expositions remain to this day as central features of the park. The buildings were intended to be temporary structures, but most remained in continuous use until they progressively fell into disrepair. Most were eventually rebuilt, using castings of the original facades to retain the architectural style.[16]The menagerie of exotic animals featured at the 1915 exposition provided the basis for the San Diego Zoo.[17]

Hand drawn illustration of Balboa Park

Balboa Park on the cover of a guidebook for the World Exposition of 1915

The southern portion of the Point Loma peninsula was set aside for military purposes as early as 1852. Over the next several decades the Army set up a series of coastal artillery batteries and named the areaFort Rosecrans.[18] Significant U.S. Navy presence began in 1901 with the establishment of the Navy Coaling Station in Point Loma, and expanded greatly during the 1920s.[19] By 1930 the city was host toNaval Base San DiegoNaval Training Center San DiegoSan Diego Naval HospitalCamp Matthews, andCamp Kearny (now Marine Corps Air Station Miramar). The city was also an early center for aviation: as early as World War I San Diego was proclaiming itself “The Air Capital of the West.”[20] The city was home to important airplane developers and manufacturers like Ryan Airlines (later Ryan Aeronautical), founded in 1925, and Consolidated Aircraft (later Convair), founded in 1923. Charles A. Lindbergh‘s planeThe Spirit of St. Louis was built in San Diego in 1927 by Ryan Airlines.[20]

During World War II, San Diego became a major hub of military and defense activity, due to the presence of so many military installations and defense manufacturers. The city’s population grew rapidly during and after World War II, more than doubling between 1930 (147,995) and 1950 (333,865).[21] After World War II, the military continued to play a major role in the local economy, but post-Cold War cutbacks took a heavy toll on the local defense and aerospace industries. The resulting downturn led San Diego leaders to seek to diversify the city’s economy by focusing on research and science, as well as tourism.[22]

From the start of the 20th century through the 1970s, the American tuna fishing fleet and tuna canning industry were based in San Diego, “the tuna capital of the world”.[23] San Diego’s first tuna cannery was founded in 1911, and by the mid-1930s the canneries employed more than 1,000 people. Due to rising costs and foreign competition, the last of the canneries closed in the early 1980s.[24] A large fishing fleet supported the canneries, mostly staffed by immigrant fishermen from Japan, and later from the Portuguese Azoresand Italy whose influence is still felt in neighborhoods like Little Italy and Point Loma.[25][26] In 1950, the Census Bureau reported San Diego’s population as 94.5% white and 4.5% black.[27]

Downtown San Diego was in decline in the 1960s and 1970s but experienced some urban renewal since the early 1980s, including the opening of Horton Plaza, the revival of the Gaslamp Quarter, and the construction of the San Diego Convention CenterPetco Parkopened in 2004.[28]


Urban arial of San Diego and Tijuana, Mexico

According to SDSU professor emeritus Monte Marshall, San Diego Bay is “the surface expression of a north-south-trending, nested graben“. The Rose Canyon and Point Lomafault zones are part of the San Andreas Fault system. About 15 miles east of the bay are the Laguna Mountains in the Peninsular Ranges, which are part of the backbone of the American continents.[29]

The city lies on approximately 200 deep canyons and hills separating its mesas, creating small pockets of natural open space scattered throughout the city and giving it a hilly geography.[30] Traditionally, San Diegans have built their homes and businesses on the mesas, while leaving the urban canyons relatively wild.[31] Thus, the canyons give parts of the city a segmented feel, creating gaps between otherwise proximate neighborhoods and contributing to a low-density, car-centered environment. The San Diego River runs through the middle of San Diego from east to west, creating a river valley which serves to divide the city into northern and southern segments. The river used to flow into San Diego Bay and its fresh water was the focus of the earliest Spanish explorers.[29] Several reservoirs andMission Trails Regional Park also lie between and separate developed areas of the city.

Notable peaks within the city limits include Cowles Mountain, the highest point in the city at 1,593 feet (486 m); Black Mountain at 1,558 feet (475 m); and Mount Soledad at 824 feet (251 m). The Cuyamaca Mountains and Laguna Mountains rise to the east of the city, and beyond the mountains are desert areas. The Cleveland National Forest is a half-hour drive from downtown San Diego. Numerous farms are found in the valleys northeast and southeast of the city.

In its 2013 ParkScore ranking, The Trust for Public Land reported that San Diego had the 9th best park system among the 50 most populous U.S. cities.[32] ParkScore ranks city park systems by a formula that analyzes acreage, access, and service and investment.

Communities and neighborhoods

The city of San Diego recognizes 52 individual areas as Community Planning Areas.[33]Within a given planning area there may be several distinct neighborhoods. Altogether the city contains more than 100 identified neighborhoods.

Downtown San Diego is located on San Diego Bay. Balboa Park encompasses several mesas and canyons to the northeast, surrounded by older, dense urban communitiesincluding Hillcrest and North Park. To the east and southeast lie City Heights, the College Area, and Southeast San Diego. To the north lies Mission Valley and Interstate 8. The communities north of the valley and freeway, and south of Marine Corps Air Station Miramar, include ClairemontKearny MesaTierrasanta, and Navajo. Stretching north from Miramar are the northern suburbs of Mira MesaScripps RanchRancho Peñasquitos, and Rancho Bernardo. The far northeast portion of the city encompasses Lake Hodges and the San Pasqual Valley, which holds an agricultural preserve. Carmel Valley and Del Mar Heights occupy the northwest corner of the city. To their south are Torrey Pines State Reserveand the business center of the Golden Triangle. Further south are the beach and coastal communities of La JollaPacific Beach, andOcean BeachPoint Loma occupies the peninsula across San Diego Bay from downtown. The communities of South San Diego, such as San Ysidro and Otay Mesa, are located next to the Mexico – United States border, and are physically separated from the rest of the city by the cities of National City and Chula Vista. A narrow strip of land at the bottom of San Diego Bay connects these southern neighborhoods with the rest of the city.

For the most part, San Diego neighborhood boundaries tend to be understood by its residents based on geographical boundaries like canyons and street patterns.[34] The city recognized the importance of its neighborhoods when it organized its 2008 General Plan around the concept of a “City of Villages”.[35]


The Skyline of Downtown San Diego during daytime, seen from Coronado, in November 2007.

The Skyline of Downtown San Diego during nighttime, seen from Coronado, in November 2007.

San Diego was originally centered in the Old Town district, but by the late 1860s the center of focus had relocated to the bayfront in the belief that this new location would increase trade. As the “New Town” – present-day Downtown – waterfront location quickly developed, it eclipsed Old Town as the center of San Diego.[36]

The development of skyscrapers over 300 feet (91 m) in San Diego is attributed to the construction of the El Cortez Apartment Hotel in 1927, the tallest building in the city from 1927 to 1963.[37] As time went on multiple buildings claimed the title of San Diego’s tallest skyscraper, including the Union Bank of California Building and Symphony Towers. Currently the tallest building in San Diego is One America Plaza, standing 500 feet (150 m) tall, which was completed in 1991.[38] The downtown skyline contains no super-talls, as a regulation put in place by the Federal Aviation Administration in the 1970s set a 500 feet (152 m) limit on the height of buildings due to the proximity of San Diego International Airport.[39] An iconic description of the skyline includes its skyscrapers being compared to the tools of a toolbox.[40]


A surfer at Black’s Beach

San Diego is one of the top-ten best climates in the Farmer’s Almanac[41] and is one of the two best summer climates in America as scored by The Weather Channel.[42] Under theKöppen-Geiger climate classification system, the San Diego area has been variously categorized as having either a semi-arid climate (BSh in the original classification)[43] and (BSkn in modified Köppen classification)[44] or a Mediterranean climate[45] (Csa) and (Csb).[46] San Diego’s climate is characterized by warm, dry summers and mild winters with most of the annual precipitation falling between December and March. The city has a mild climate year-round,[47] with an average of 201 days above 70 °F (21 °C) and low rainfall (9–13 inches [23–33 cm] annually).

The climate in San Diego, like most of Southern California, often varies significantly over short geographical distances resulting in microclimates. In San Diego, this is mostly because of the city’s topography (the Bay, and the numerous hills, mountains, and canyons). Frequently, particularly during the “May gray/June gloom” period, a thick “marine layer” cloud cover will keep the air cool and damp within a few miles of the coast, but will yield to bright cloudless sunshine approximately 5–10 miles (8.0–16 km) inland.[48] Sometimes the June gloom can last into July, causing cloudy skies over most of San Diego for the entire day.[49][50] Even in the absence of June gloom, inland areas tend to experience much more significant temperature variations than coastal areas, where the ocean serves as a moderating influence. Thus, for example, downtown San Diego averages January lows of50 °F (10 °C) and August highs of 78 °F (26 °C). The city of El Cajon, just 10 miles (16 km) inland from downtown San Diego, averages January lows of 42 °F (6 °C) and August highs of 88 °F (31 °C).

A sign of global warming, scientists at Scripps Institution of Oceanography say the average surface temperature of the water at Scripps Pier in the California Current has increased by almost 3 degrees since 1950.[51]

Several people, some wearing full length suits and carrying surf boards, on a beachfront with houses visible above them

Surfers in Pacific Beach

Rainfall along the coast averages about 10 inches (250 mm) of precipitation annually. The average (mean) rainfall is 10.65 inches (271 mm) and the median is 9.6 inches (240 mm).[52]Most of the rainfall occurs during the cooler months. The months of December through March supply most of the rain, with February the only month averaging 2 inches (51 mm) or more of rain. The months of May through September tend to be almost completely dry. Though there are few wet days per month during the rainy period, rainfall can be heavy when it does fall. Rainfall is usually greater in the higher elevations of San Diego; some of the higher elevation areas of San Diego can receive 11–15 inches (280–380 mm) of rain a year. Variability of rainfall can be extreme: in the wettest years of 1883/1884 and 1940/1941 more than 24 inches (610 mm) fell in the city, whilst in the driest years as little as 3.2 inches (80 mm) has fallen for a full year. The wettest month on record has been December 1921 with 9.21 inches (234 mm).

Snow in the city is so rare that it has been observed only five times in the century-and-a-half that records have been kept. In 1949 and 1967, snow stayed on the ground for a few hours in higher locations like Point Loma and La Jolla. The other three occasions, in 1882, 1946, and 1987, involved flurries but no accumulation.[53]

Official temperature record-keeping began in San Diego in 1872,[54] although other weather records go back further. The city’s first official weather station was at Mission San Diego from 1849 to 1858. From August 1858 until 1940, the official weather station was at a series of downtown buildings, and the station has been at Lindbergh Field since February 1940.[55]


[hide]Climate data for San Diego Int’l Airport (1981–2010 normals)
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Average high °F (°C) 65.1
Average low °F (°C) 49.0
Rainfall inches (mm) 1.98
Avg. rainy days (≥ 0.01 in) 6.7 7.1 6.5 4.0 1.4 0.8 0.7 0.4 1.2 2.8 4.1 5.8 41.5
Mean monthly sunshine hours 239.3 227.4 261.0 276.2 250.5 242.4 304.7 295.0 253.3 243.4 230.1 231.3 3,054.6
Source: NOAA (sun 1961–1990)[56][57]



Torrey Pines State Park Valley

Coastal canyon in Torrey Pines State Reserve

Like most of southern California, the majority of San Diego’s current area was originally occupied by chaparral, a plant community made up mostly of drought-resistant shrubs. The endangered Torrey Pine has the bulk of its population in San Diego in a stretch of protected chaparral along the coast. The steep and varied topography and proximity to the ocean create a number of different habitats within the city limits, including tidal marsh andcanyons. The chaparral and coastal sage scrub habitats in low elevations along the coast are prone to wildfire, and the rates of fire have increased in the 20th century, due primarily to fires starting near the borders of urban and wild areas.[58]

San Diego’s broad city limits encompass a number of large nature preserves, includingTorrey Pines State ReserveLos Peñasquitos Canyon Preserve, and Mission Trails Regional Park. Torrey Pines State Reserve and a coastal strip continuing to the north constitute the only location where the rare species of Torrey Pine, P. torreyana torreyana, is found.[59]

San Diego against Witch Creek Fire smoke

San Diego viewed against the Witch Creek Fire smoke

Due to the steep topography that prevents or discourages building, along with some efforts for preservation, there are also a large number of canyons within the city limits that serve as nature preserves, including Switzer Canyon, Tecolote Canyon Natural Park,[60] and Marian Bear Memorial Park in the San Clemente Canyon,[61] as well as a number of small parks and preserves.

San Diego County has one of the highest counts of animal and plant species that appear on the endangered species list among counties in the United States.[62] Because of its diversity of habitat and its position on the Pacific Flyway, San Diego County has recorded the presence of 492 bird species, more than any other region in the country.[63] San Diego always scores very high in the number of bird species observed in the annual Christmas Bird Count, sponsored by the Audubon Society, and it is known as one of the “birdiest” areas in the United States.[64][65]

San Diego and its backcountry are subject to periodic wildfires. In October 2003, San Diego was the site of the Cedar Fire, which has been called the largest wildfire in California over the past century.[66] The fire burned 280,000 acres (1,130 km2), killed 15 people, and destroyed more than 2,200 homes.[67] In addition to damage caused by the fire, smoke resulted in a significant increase in emergency room visits due to asthma, respiratory problems, eye irritation, and smoke inhalation; the poor air quality caused San Diego County schools to close for a week.[68] Wildfires four years later destroyed some areas, particularly within the communities of Rancho BernardoRancho Santa Fe, and Ramona.[69]


The city had a population of 1,307,402 in 2010, according to the census that year, on a land area of 372.1 square miles (963.7 km2). The urban area of San Diego extends beyond the administrative city limits and had a total 2010 population of 2,880,000, making it thethird-largest urban area in the state, after Los Angeles metropolitan area and San Francisco metropolitan area.

Historical populations
Census Pop.
1850 500
1860 731 46.2%
1870 2,300 214.6%
1880 2,637 14.7%
1890 16,159 512.8%
1900 17,700 9.5%
1910 39,578 123.6%
1920 74,361 87.9%
1930 147,995 99.0%
1940 203,341 37.4%
1950 333,865 64.2%
1960 573,224 71.7%
1970 696,769 21.6%
1980 875,538 25.7%
1990 1,110,549 26.8%
2000 1,223,400 10.2%
2010 1,307,402 6.9%
Est. 2012 1,338,348 [70] 2.4%

As of the Census of 2010, there were 1,307,402 people living in the city of San Diego.[72] That represents a population increase of just under 7% from the 1,223,400 people, 450,691 households, and 271,315 families reported in 2000.[73] The estimated city population in 2009 was 1,306,300. The population density was 3,771.9 people per square mile (1,456.4/km2). The racial makeup of San Diego was 58.9% White, 6.7% African American, 0.6% Native American, 15.9% Asian (5.9%Filipino, 2.7% Chinese, 2.5% Vietnamese, 1.3% Indian, 1.0% Korean, 0.7% Japanese, 0.4%Laotian, 0.3% Cambodian, 0.1% Thai). 0.5% Pacific Islander, 12.3% from other races, and 5.1% from two or more races. The ethnic makeup of the city was 28.8% Hispanic or Latino (of any race), putting the non-Hispanic or Latino population (of any race) at 71.2%.[74][75] 24.9% of the total population were Mexican American, and 0.6% were Puerto Rican.

As of December 2012, San Diego has the third largest homeless population in the United States;[76] the city’s homeless population has the largest percentage of homeless veterans in the nation.[76]

A U.S. Navy vice admiral and an intelligence specialist celebrating Hispanic American Heritage Month in San Diego

As of January 1, 2008 estimates by the San Diego Association of Governments revealed that the household median income for San Diego rose to $66,715, up from $45,733, and that the city population rose to 1,336,865, up 9.3% from 2000.[77] The population was 45.3% non-Hispanic whites, down from 78.9% in 1970,[27] 27.7% Hispanics, 15.6% Asians/Pacific Islanders, 7.1% blacks, 0.4% American Indians, and 3.9% from other races. Median age of Hispanics was 27.5 years, compared to 35.1 years overall and 41.6 years among non-Hispanic whites; Hispanics were the largest group in all ages under 18, and non-Hispanic whites constituted 63.1% of population 55 and older.

In 2000 there were 451,126 households out of which 30.2% had children under the age of 18 living with them, 44.6% were married couples living together, 11.4% had a female householder with no husband present, and 39.8% were non-families. Households made up of individuals account for 28.0% and 7.4% had someone living alone who was 65 years of age or older. The average household size was 2.61 and the average family size was 3.30.

The U.S. Census Bureau reported that in 2000, 24.0% of San Diego residents were under 18, and 10.5% were 65 and over.[78] The median age was 32; two-thirds of the population was under 35.[79] The San Diego County regional planning agency, SANDAG, provides tables and graphs breaking down the city population into 5-year age groups.[80] In 2000, the median income for a household in the city was $45,733, and the median income for a family was $53,060.[81] Males had a median income of $36,984 versus $31,076 for females. The per capita income for the city was $23,609.[81] According to Forbes in 2005, San Diego was the fifth wealthiest U.S. city[82] but about 10.6% of families and 14.6% of the population were below the poverty line, including 20.0% of those under age 18 and 7.6% of those age 65 or over.[81] Nonetheless, San Diego was rated the fifth-best place to live in the United States in 2006 by Moneymagazine.[83]


According to Forbes magazine, San Diego was the ninth-safest city in the top 10 list of safest cities in the U.S. in 2010.[84] Like most major cities, San Diego had a declining crime rate from 1990 to 2000. Crime in San Diego increased in the early 2000s.[85][86][87] In 2004, San Diego had the sixth lowest crime rate of any U.S. city with over half a million residents.[87] From 2002 to 2006, the crime rate overall dropped 0.8%, though not evenly by category. While violent crime decreased 12.4% during this period, property crime increased 1.1%. Total property crimes per 100,000 people were lower than the national average in 2008.[88]

According to Uniform Crime Report statistics compiled by the Federal Bureau of Investigation (FBI) in 2010, there were 5,616 violent crimes and 30,753 property crimes per 100,000 residents. Of these, the violent crimes consisted of forcible rapes, 73 robberies and 170 aggravated assaults, while 6,387 burglaries, 17,977 larceny-thefts, 6,389 motor vehicle thefts and 155 arson defined the property offenses.[89]


The largest sectors of San Diego’s economy are defense/military, tourism, international trade, and research/manufacturing, respectively.[90][91]

Defense and military

The economy of San Diego is influenced by its deepwater port, which includes the only major submarine and shipbuilding yards on the West Coast.[92] Several major national defense contractors were started and are headquartered in San Diego, including General AtomicsCubic, and NASSCO.[93][94]

San Diego hosts the largest naval fleet in the world:[95] it was in 2008 was home to 53 ships, over 120 tenant commands, and more than 35,000 sailors, soldiers, Department of Defense civilian employees and contractors.[96] About 5 percent of all civilian jobs in the county are military-related, and 15,000 businesses in San Diego County rely on Department of Defense contracts.[96]

F/A-18 Hornet flying over San Diego and the USS John C. Stennis

Military bases in San Diego include US Navy facilities, Marine Corps bases, and Coast Guard stations. Marine Corps institutions in the city of San Diego include Marine Corps Air Station Miramar and Marine Corps Recruit Depot San Diego. The Navy has several institutions in the city, including Naval Base Point Loma,Naval Base San Diego (also known as the 32nd Street Naval Station), Naval Medical Center San Diego (also known as Bob Wilson Naval Hospital), the Space and Naval Warfare Systems Center San Diego, and Space and Naval Warfare Systems Command(“SPAWAR”). Also near San Diego but not within the city limits are Naval Amphibious Base Coronado and Naval Air Station North Island (which operates Naval Auxiliary Landing Facility San Clemente IslandSilver Strand Training Complex, and the Outlying Field Imperial Beach). San Diego is known as the “birthplace of naval aviation“.[97]

The city is “home to the majority of the U.S. Pacific Fleet’s surface combatants, all of the Navy’s West Coast amphibious ships and a variety of Coast Guard and Military Sealift Command vessels”.[96][98] Two Nimitz class supercarriers, (the USS Carl Vinson, and USS Ronald Reagan),[99][100][101] fiveamphibious assault ships, several Los Angeles-class “fast attack” submarines, the Hospital Ship USNS Mercy,[102][103] carrier and submarine tenders, destroyerscruisersfrigates, and many smaller ships are home-ported there.[100] Four Navy vessels have been named USS San Diego.[104]


Downtown San Diego, California

Tourism is a major industry owing to the city’s climate, its beaches, and numerous tourist attractions such as Balboa ParkBelmont amusement park, San Diego ZooSan Diego Zoo Safari Park, and SeaWorld San Diego. San Diego’s Spanish and Mexican heritage is reflected in the many historic sites across the city, such as Mission San Diego de Alcalaand Old Town San Diego State Historic Park. Annual events in San Diego include Comic-Con, the Farmers Insurance Open golf tournament, San Diego Pride, the San Diego Black Film Festival, and Street Scene Music Festival. Also, the local craft brewing industry attracts an increasing number of visitors[105] for “beer tours” and the annual San Diego Beer Week in November;[106] San Diego has been called “America’s Craft Beer Capital.”[107]

San Diego County hosted more than 32 million visitors in 2012, of whom approximately half stayed overnight and half were day visitors; collectively they spent an estimated $8 billion locally, with a regional economic impact of more than $18 billion. The visitor industry provides employment for more than 160,000 people.[108] The San Diego Convention Centerhosted 68 out-of-town conventions and trade shows in 2009, attracting more than 600,000 visitors.[108] Transient Occupancy Taxes (TOT) have created funding for the City of San Diego Commission for Arts and Culture.[109]

San Diego’s cruise ship industry used to be the second largest in California. Each cruise ship call injects an estimated $2 million (from the purchase of food, fuel, supplies, and maintenance services, not counting the money spent by the tourists) into the local economy.[110] Numerous cruise lines, including Carnival, Holland America, Celebrity, Crystal and Princess, operate out of San Diego. However, cruise ship business has been in steady decline since peaking in 2008, when the Port hosted over 250 ship calls and more than 900,000 passengers. By 2011 the number of ship calls had fallen to 103 (estimated).[111] Holland America and Carnival Cruises operated weekly cruises to the Mexican Riviera for many years, but both ended their regular scheduled service in spring 2012, which was an economic loss to the region of more than $100 million.[111] The decline is blamed on the slumping economy as well as fear of travel to Mexico due to well-publicized violence there.[112]

There are local cruises in San Diego Bay and Mission Bay, available through companies such as Hornblower and H&M. These include sightseeing and “sunset” cruises as well as private-event or “party” cruises. Also available are whale watching cruises to observe the migration of tens of thousands of gray whales that pass by San Diego, peaking in mid-January,[113] and year-round sport fishing expeditions.

International trade

Downtown of San Diego

San Diego’s commercial port and its location on the United States-Mexico border make international trade an important factor in the city’s economy. The city is authorized by the United States government to operate as a Foreign Trade Zone.[114]

The city shares a 15-mile (24 km) border with Mexico that includes two border crossings. San Diego hosts the busiest international border crossing in the world, in the San Ysidro neighborhood at the San Ysidro Port of Entry.[115] A second, primarily commercial border crossing operates in the Otay Mesa area; it is the largest commercial crossing on the California-Baja California border and handles the third highest volume of trucks and dollar value of trade among all United States-Mexico land crossings.[116]

One of the Port of San Diego’s two cargo facilities is located in Downtown San Diego at the Tenth Avenue Marine Terminal. This terminal has facilities for containers, bulk cargo, and refrigerated and frozen storage, so that it can handle the import and export of perishables (including 33 million bananas every month) as well as fertilizer, cement, forest products, and other commodities.[117] In 2009 the Port of San Diego handled 1,137,054 short tons of total trade; foreign trade accounted for 956,637 short tons while domestic trade amounted to 180,417 short tons.[118]

Manufacturing and research

Modern five story office building

Qualcomm corporate headquarters

In 2010, former Governor Schwarzenegger’s Office of Economic Development designated San Diego as an iHub Innovation Center for collaboration potentially between wireless and life sciences, citing the area’s wireless business, pharmaceutical research and start-ups for medical devices and diagnostics.[119]

San Diego hosts several major producers of wireless cellular technology. Qualcomm was founded and is headquartered in San Diego, and still is the largest private-sector technology employer (excluding hospitals) in San Diego County.[120] Other wireless industry manufacturers headquartered here include NokiaLG Electronics,[121] Kyocera International.,[122] Cricket Communications and Novatel Wireless.[123] According to the San Diego Business Journal, the largest software company in San Diego is security software company Websense Inc.[124] San Diego also has the U.S. headquarters for the Slovakiansecurity company ESET.[125]

The presence of the University of California, San Diego and other research institutions has helped to fuel biotechnology growth.[126] In June 2004, San Diego was ranked the top biotech cluster in the United States by the Milken Institute.[127] In 2013, San Diego has the second largest biotech cluster in the United States, below the Boston area and above the San Francisco Bay Area.[128] There are more than 400 biotechnology companies in the area.[129] In particular, the La Jolla and nearby Sorrento Valley areas are home to offices and research facilities for numerous biotechnology companies.[130] Major biotechnology companies like Neurocrine Biosciences and Nventa Biopharmaceuticals are headquartered in San Diego, while many biotech and pharmaceutical companies, such as BD Biosciences,Biogen IdecIntegrated DNA TechnologiesMerckPfizerÉlanCelgene, and Vertex, have offices or research facilities in San Diego. There are also several non-profit biotech and health care institutes, such as the Salk Institute for Biological Studiesthe Scripps Research Institute, the West Wireless Health Institute and the Sanford-Burnham Institute. San Diego is also home to more than 140contract research organizations (CROs) that provide a variety of contract services for pharmaceutical and biotechnology companies.[131]

Historically tuna fishing and canning was one of San Diego’s major industries,[132] and although the American tuna fishing fleet is no longer based in San Diego, seafood companies Bumble Bee Foods and Chicken of the Sea are still headquartered there.[133][134]

Real estate

Skyline view of the Village of La Jolla in San Diego

Prior to 2006, San Diego experienced a dramatic growth of real estate prices, to the extent that the situation was sometimes described as a “housing affordability crisis”. Median single family home prices more than tripled between 1998 and 2007. According to the California Association of Realtors, in May 2007 a median house in San Diego cost $612,370.[135] Growth of real estate prices was not accompanied by comparable growth of household incomes: the Housing Affordability Index (percentage of households that can afford to buy a median-priced house) fell below 20 percent in the early 2000s. The San Diego metropolitan area had one of the worst median multiples (ratio of median house price to median household income) of all metropolitan areas in the United States,[136] a situation sometimes referred to as aSunshine tax. As a consequence, San Diego experienced negative net migration since 2004. A significant number of people moved to adjacent Riverside County, commuting daily from Temecula and Murrieta to jobs in San Diego. Many of San Diego’s home buyers tend to buy homes within the more affordable neighborhoods, while others are leaving the state altogether and moving to more affordable regions of the country.[137]

San Diego home prices peaked in 2005, then declined as part of a nationwide trend. As of December 2010, home prices were 60 percent higher than in 2000, but down 36 percent from the peak in 2005.[138] The median home price declined by more than $200,000 between 2005 and 2010, and sales dropped by 50 percent.[139]

Top employers

According to the City’s 2012 Comprehensive Annual Financial Report,[140] the top employers in the city are:

Round seal with a bird in front. Words around the edge say Department of the Navy, United States of America

The United States Navy is San Diego’s second largest employer.

Employer Number of employees
University of California, San Diego 28,071
United States Navy 27,869
Sharp HealthCare 15,366
San Diego County 15,171
San Diego Unified School District 13,633
Qualcomm 11,877
City of San Diego 9,841
Kaiser Permanente 7,425
UC San Diego Health System 6,039
San Diego Gas & Electric 5,028


Public schools in San Diego are operated by independent school districts. The majority of the public schools in the city are served by the San Diego Unified School District, also the second largest school district in California, which includes 11 K-8 schools, 107 elementary schools, 24 middle schools, 13 atypical and alternative schools, 28 high schools, and 45 charter schools.[141] Several adjacent school districts which are headquartered outside the city limits serve some schools within the city; these include the Poway Unified School DistrictDel Mar Union School DistrictSan Dieguito Union High School District and Sweetwater Union High School District. In addition, there are a number of private schools in the city.

Colleges and universities

San Diego State University’s Hepner Hall

According to education rankings released by the U.S. Census Bureau, 40.4 percent of San Diegans ages 25 and older hold bachelor’s degrees. The census ranks the city as the ninth most educated city in the United States based on these figures.[142]

Public colleges and universities in the city include San Diego State University (SDSU),University of California, San Diego (UCSD), and the San Diego Community College District, which includes San Diego City CollegeSan Diego Mesa College, and San Diego Miramar College. Private colleges and universities in the city include University of San Diego (USD),Point Loma Nazarene University (PLNU), Alliant International University (AIU), National UniversityCalifornia International Business University (CIBU), San Diego Christian College,John Paul the Great Catholic UniversityCalifornia College San DiegoColeman University,University of Redlands School of Business, Design Institute of San Diego (DISD), Fashion Institute of Design & Merchandising‘s San Diego campus, NewSchool of Architecture and DesignPacific Oaks College San Diego Campus, Chapman University‘s San Diego Campus, The Art Institute of California-San Diego,Southern States University (SSU), UEI College, and Woodbury University School of Architecture’s satellite campus.

There is one medical school in the city, the UCSD School of Medicine. There are three ABA accredited law schools in the city, which include California Western School of LawThomas Jefferson School of Law, and University of San Diego School of Law. There is also one unaccredited law school, Western Sierra Law School.


University of California, San Diego‘sGeisel Library, named for Theodor Seuss Geisel (“Dr. Seuss“)

The city-run San Diego Public Library system is headquartered downtown and has 34 branches throughout the city.[143] The libraries have had reduced operating hours since 2003 due to the city’s financial problems. In 2006 the city increased spending on libraries by $2.1 million.[144] A new nine-story Central Library is under construction on Park Boulevard at J Street.[145]

In addition to the municipal public library system, there are nearly two dozen libraries open to the public which are run by other governmental agencies and by schools, colleges, and universities.[146] Noteworthy among them are the Malcolm A. Love Library at San Diego State University and the Geisel Library at the University of California, San Diego.


Main article: Culture of San Diego

Many popular museums, such as the San Diego Museum of Art, the San Diego Natural History Museum, the San Diego Museum of Man, and the Museum of Photographic Arts are located in Balboa Park. The Museum of Contemporary Art San Diego (MCASD) is located in La Jolla and has a branch located at the Santa Fe Depot downtown. The Columbia district downtown is home to historic ship exhibits belonging to the San Diego Maritime Museum, headlined by the Star of India, as well as the unrelated San Diego Aircraft Carrier Museum featuring the USS Midway aircraft carrier.

The San Diego Symphony at Symphony Towers performs on a regular basis and is directed by Jahja Ling. The San Diego Opera at Civic Center Plaza, directed by Ian Campbell, was ranked by Opera America as one of the top 10 opera companies in the United States. Old Globe Theatre at Balboa Park produces about 15 plays and musicals annually. The La Jolla Playhouse at UCSD is directed by Christopher Ashley. Both the Old Globe Theatre and the La Jolla Playhouse have produced the world premieres of plays and musicals that have gone on to win Tony Awards[147] or nominations[148]on Broadway. The Joan B. Kroc Theatre at Kroc Center’s Performing Arts Center is a 600-seat state-of-the-art theatre that hosts music, dance, and theatre performances. The San Diego Repertory Theatre at the Lyceum Theatres in Horton Plaza produces a variety of plays and musicals. Other professional theatrical production companies include the Lyric Opera San Diego and the Starlight Musical Theatre. Hundreds of movies and a dozen TV shows have been filmed in San Diego, a tradition going back as far as 1898.[149]

SDSU raises the Pride Flag during Pride Week in front of Hepner Hall

San Diego was named the 9th most LGBT-friendly city in the U.S. in 2013.[150] The city also has the 7th highest percentage of gay residents in the U.S. Additionally in 2013,San Diego State University (SDSU), one of the city’s prominent universities, was named one of the top LGBT-friendly campuses in the nation.[151]


Full stands, both teams on the field, cheerleaders and lots of people milling around

Qualcomm Stadium (formerly named “Jack Murphy Stadium” after a sports writer) hosts a San Diego Chargers game with theSt. Louis Rams.

Main article: Sports in San Diego

The National Football League‘s San Diego Chargers play in Qualcomm Stadium. Three NFL Super Bowl championships have been held there. Major League Baseball‘s San Diego Padres play in Petco Park. Parts of the World Baseball Classic were played there in 2006 and 2009.

NCAA Division I San Diego State Aztecs men’s and women’s basketball games are played at Viejas Arena at Aztec Bowl on the campus of San Diego State UniversityCollege footballand soccer, basketball and volleyball are played at the Torero Stadium and the Jenny Craig Pavilion at USD.

The San Diego State Aztecs (MWC) and the University of San Diego Toreros (WCC) are NCAA Division I teams. The UCSD Tritons (CCAA) are members of NCAA Division II while the Point Loma Nazarene Sea Lions and San Diego Christian College (GSAC) are members of theNAIA.

Qualcomm stadium also houses the NCAA Division I San Diego State Aztecs, as well as local high school football championships, international soccer games, and supercrossevents. Two of college football’s annual bowl games are also held there: the Holiday Bowland the Poinsettia Bowl. Soccer, American football, and track and field are played in Balboa Stadium, the city’s first stadium, constructed in 1914.

Rugby union is a developing sport in the city. The USA Sevens, a major rugby event, was held there from 2007 through 2009. San Diego is one of only 16 cities in the United States included in the Rugby Super League[152] represented by Old Mission Beach Athletic Club RFC, the home club of USA Rugby‘s Captain Todd Clever who plays rugby professionally in Japan’s Top League with Suntory Sungoliath.[153] San Diego will participate in the Western American National Rugby League which starts in 2011.[154]

The San Diego Surf of the American Basketball Association is located in the city. The annual Farmers Insurance Open golf tournament (formerly the Buick Invitational) on the PGA Tour occurs at the municipally owned Torrey Pines Golf Course. This course was also the site of the 2008 U.S. Open Golf Championship. The San Diego Yacht Club hosted the America’s Cup yacht races three times during the period 1988 to 1995. The amateur beach sport Over-the-line was invented in San Diego,[155] and the annual world Over-the-line championships are held at Mission Bay every year.[156]


The following are published within the city: the daily newspaper, U-T San Diego and its online portal, of the same name,[157] and the alternative newsweeklies, the San Diego CityBeat and San Diego ReaderVoice of San Diego is a non-profit online-only news outlet covering government, politics, education, neighborhoods, and the arts. The San Diego Daily Transcript is a business-oriented daily newspaper.

Several buildings in front with signs for various stores, high skyscraper behind them on left with NBC logo

NBC San Diego (left) is outsideHorton Plaza on Broadway downtown.

San Diego led U.S. local markets with 69.6 percent broadband penetration in 2004 according toNielsen//NetRatings.[158]

San Diego’s first television station was KFMB, which began broadcasting on May 16, 1949.[159]Since the Federal Communications Commission (FCC) licensed seven television stations in Los Angeles, two VHF channels were available for San Diego because of its relative proximity to the larger city. In 1952, however, the FCC began licensing UHF channels, making it possible for cities such as San Diego to acquire more stations. Stations based in Mexico (with ITU prefixes of XE and XH) also serve the San Diego market. Television stations today include XHTJB 3 (Once TV), XETV 6 (CW), KFMB 8 (CBS), KGTV 10 (ABC), XEWT 12 (Televisa Regional), KPBS 15 (PBS), KBNT-CD 17 (Univision), XHTIT 21 (Azteca 7), XHJK 27 (Azteca 13), KSDX-LP 29 (Spanish Independent), XHAS 33 (Telemundo), K35DG 35 (UCSD-TV), KDTF-LD 51 (Telefutura), KNSD 39 (NBC), KZSD-LP 41 (Azteca America), KSEX-CD 42 (Infomercials), XHBJ 45 (Canal 5), XHDTV 49 (MNTV), KUSI 51 (Independent), XHUAA 57 (Canal de las Estrellas), and KSWB-TV 69 (Fox). San Diego has an 80.6 percent cable penetration rate.[160]

Due to the ratio of U.S. and Mexican-licensed stations, San Diego is the largest media market in the United States that is legally unable to support a television station duopoly between two full-power stations under FCC regulations, which disallow duopolies in metropolitan areas with fewer than nine full-power television stations and require that there must be eight unique station owners that remain once a duopoly is formed (there are only seven full-power stations on the California side of the San Diego-Tijuana market).[citation needed] Though the E. W. Scripps Company owns KGTV and KZSD-LP, they are not considered a duopoly under the FCC’s legal definition as common ownership between full-power and low-power television stations in the same market is permitted regardless to the number of stations licensed to the area. As a whole, the Mexico side of the San Diego-Tijuana market has two duopolies and one triopoly (Entravision Communications owns both XHAS-TV and XHDTV-TV, TV Azteca owns XHJK-TV and XHTIT-TV, and Grupo Televisa owns XHUAA-TV and XHWT-TV along with being the license holder for XETV-TV, which is run by California-based subsidiary Bay City Television).

The radio stations in San Diego include nationwide broadcaster, Clear Channel CommunicationsCBS Radio, Midwest Television,Lincoln Financial Media, Finest City Broadcasting, and many other smaller stations and networks. Stations include: KOGO AM 600,KFMB AM 760KCEO AM 1000KCBQ AM 1170K-PraiseKLSD AM 1360 Air AmericaKFSD 1450 AMKPBS-FM 89.5, Channel 933Star 94.1FM 94/9FM News and Talk 95.7Q96 96.1, KyXy 96.5, Free Radio San Diego (AKA Pirate Radio San Diego) 96.9FM FRSD, KSON 97.3/92.1, KIFM 98.1, Jack-FM 100.7, 101.5 KGB-FMKPRI 102.1, Rock 105.3, and another Pirate Radio station at 106.9FM, as well as a number of local Spanish-language radio stations.


Local government

Waist high portrait of man in his sixties, smiling in a black suit

Mayor Bob Filner

The city is governed by a mayor and a 9-member city council. In 2006, the city’s form of government changed from a council–manager government to a strong mayor government. The change was brought about by a citywide vote in 2004. The mayor is in effect the chief executive officer of the city, while the council is the legislative body.[161] The City of San Diego is responsible for police, public safety, streets, water and sewer service, planning and zoning, and similar services within its borders. San Diego is a sanctuary city,[162] however, San Diego County is a participant of the Secure Communities program.[163][164]

The members of the city council are each elected from single member districts within the city. The mayor and city attorney are elected directly by the voters of the entire city. The mayor, city attorney, and council members are elected to four-year terms, with a two-term limit.[165]Elections are held on a non-partisan basis per California state law; nevertheless, most officeholders do identify themselves as either Democrats or Republicans. In 2007, registered Democrats outnumbered Republicans by about 7 to 6 in the city,[166] and Democrats currently hold a 5–4 majority in the City Council.

San Diego is part of San Diego County, and includes all or part of the 1st, 2nd, 3rd and 4th supervisorial districts of the San Diego County Board of Supervisors,[167] Other county officers elected in part by city residents include the SheriffDistrict AttorneyAssessor/Recorder/County Clerk, and Treasurer/Tax Collector.

Areas of the city immediately adjacent to San Diego Bay (“tidelands“) are administered by the Port of San Diego, a quasi-governmental agency which owns all the property in the tidelands and is responsible for its land use planning, policing, and similar functions. San Diego is a member of the regional planning agency San Diego Association of Governments (SANDAG). Public schools within the city are managed and funded by independent school districts (see above).

State and federal

San Diego Presidential Election Results[citation needed]
Year Democratic Republican Ref.
2012 52.58% 626,957 45.02% 536,726
2008 54.15% 666,581 43.95% 541,032
2004 46.39% 526,437 52.52% 596,033
2000 45.66% 437,666 49.63% 475,736
1996 44.11% 389,964 45.57% 402,876
1992 37.20% 367,397 35.70% 352,125
1988 38.30% 333,264 60.20% 523,143
1984 33.40% 257,029 65.30% 502,344
1980 27.30% 195,410 60.80% 435,910
1976 41.60% 263,654 55.70% 353,302
1972 34.30% 206,455 61.80% 371,627
1968 36.10% 167,669 56.30% 261,540
1964 49.70% 211,808 50.30% 214,445
1960 43.30% 171,259 56.40% 223,056

In the state legislature San Diego is located in the 39th and 40th Senate Districts, represented by Democrats Marty Block and Ben Hueso.

Portions of San Diego are in the 77th, 78th, 79th and 80th Assembly Districts, represented by Republican Brian Maienschein and Democrats Toni AtkinsShirley Weber and Lorena Gonzalez, respectively.

Federally, San Diego is located in California’s 51st52nd, and 53rd congressional districts, which are represented by Democrats Juan VargasScott Peters, and Susan Davis, respectively.

Major scandals

San Diego was the site of the 1912 San Diego Free Speech Fight, in which the city restricted speech, vigilantes brutalized and tortured anarchists, and the San Diego Police Department killed an IWW member.

In 1916, rainmaker Charles Hatfield was blamed for $4 million in damages and accused of causing San Diego’s worst flood, during which about 20 Japanese American farmers died.[168]

Then-mayor Roger Hedgecock was forced to resign his post in 1985, after he was found guilty of one count of conspiracy and twelve counts of perjury, related to the alleged failure to report all campaign contributions.[169][170] After a series of appeals, the twelve perjury counts were dismissed in 1990 based on claims of juror misconduct; the remaining conspiracy count was reduced to a misdemeanor and then dismissed.[171]

A 2002 scheme to underfund pensions for city employees led to the San Diego pension scandal. This resulted in the resignation of newly re-elected Mayor Dick Murphy[172] and the criminal indictment of six pension board members.[173] Those charges were finally dismissed by a federal judge in 2010.[174]

On November 28, 2005, U.S. Congressman Randy “Duke” Cunningham resigned after being convicted on federal bribery charges. He had represented California’s 50th congressional district, which includes much of the northern portion of the city of San Diego. In 2006, Cunningham was sentenced to a 100-month prison sentence.[175]

In 2005 two city council members, Ralph Inzunza and Deputy Mayor Michael Zucchet — who briefly took over as Acting Mayor when Murphy resigned – were convicted of extortion, wire fraud, and conspiracy to commit wire fraud for taking campaign contributions from a strip club owner and his associates, allegedly in exchange for trying to repeal the city’s “no touch” laws at strip clubs.[176] Both subsequently resigned. In 2009, a judge acquitted Zucchet on seven out of the nine counts against him, and granted his petition for a new trial on the other two charges;[177] the remaining charges were eventually dropped.[178]

In July 2013, several former supporters of Mayor Bob Filner asked him to resign because of allegations of repeated sexual harassment. Filner apologized, said he would apologize to the individuals involved, and said he was seeking help.[179] Prominent former allies, including former councilwoman Donna Frye, council president Todd Gloria, state assemblywomen Toni Atkins and Lorena Gonzalez, and several council colleagues publicly asked Filner to step down.[180] Filner’s chief of staff resigned.[181]



Water is supplied to residents by the Water Department of the City of San Diego. The city receives its water from the Metropolitan Water District of Southern California.

Gas and electric utilities are provided by San Diego Gas & Electric, a division of Sempra Energy.


I-5 looking south toward downtown San Diego

With the automobile being the primary means of transportation for over 80 percent of its residents, San Diego is served by a network of freeways and highways. This includesInterstate 5, which runs south to Tijuana and runs north to Los Angeles; Interstate 8, which runs east to Imperial County and the Arizona Sun Corridor; Interstate 15, which runs northeast through the Inland Empire to Las Vegas; and Interstate 805, which splits from I-5 near the Mexican border and rejoins I-5 at Sorrento Valley.

Major state highways include SR 94, which connects downtown with I-805, I-15 and East CountySR 163, which connects downtown with the northeast part of the city, intersects I-805 and merges with I-15 at MiramarSR 52, which connects La Jolla with East Countythrough Santee and SR 125SR 56, which connects I-5 with I-15 through Carmel Valley andRancho PeñasquitosSR 75, which spans San Diego Bay as the San Diego-Coronado Bridge, and also passes through South San Diego as Palm Avenue; and SR 905, which connects I-5 and I-805 to the Otay Mesa Port of Entry.

The stretch of SR 163 that passes through Balboa Park is San Diego’s oldest freeway, and has been called one of America’s most beautiful parkways.[182]

San Diego’s roadway system provides an extensive network of routes for travel by bicycle. The dry and mild climate of San Diego makes cycling a convenient and pleasant year-round option. At the same time, the city’s hilly, canyon-like terrain and significantly long average trip distances—brought about by strict low-density zoning laws—somewhat restrict cycling for utilitarian purposes. Older and denser neighborhoods around the downtown tend to be utility cycling oriented. This is partly because of the grid street patterns now absent in newer developments farther from the urban core, where suburban style arterial roads are much more common. As a result, a vast majority of cycling-related activities are recreational. Testament to San Diego’s cycling efforts, in 2006, San Diego was rated as the best city for cycling for U.S. cities with a population over 1 million.[183]

View of Coronado and San Diego from the air

San Diego is served by the San Diego Trolley light rail system,[184] by the SDMTS bus system,[185] and by Coaster[186] and Amtrak Pacific Surfliner[187] commuter rail; northern San Diego county is also served by the SPRINTER light rail line.[188] The Trolley primarily serves downtown and surrounding urban communities, Mission Valley, east county, and coastal south bay. A planned Mid-Coast line will operate from Old Town to University City and the University of California, San Diego along the I-5 Freeway. The Amtrak and Coaster trains currently run along the coastline and connect San Diego with Los Angeles, Orange County, Riverside, San Bernardino, and Ventura via Metrolink and the Pacific Surfliner. There are two Amtrak stations in San Diego, in Old Town and the Santa Fe Depot downtown. San Diego transit information about public transportation and commuting is available on the Web and by dialing “511” from any phone in the area.[189]

The city’s primary commercial airport is the San Diego International Airport (SAN), also known as Lindbergh Field. It is the busiest single-runway airport in the United States.[190] It served over 17 million passengers in 2005, and is dealing with an increasingly larger number every year.[190] It is located on San Diego Bay three miles (4.8 km) from downtown. San Diego International Airport maintains scheduled flights to the rest of the United States including Hawaii, as well as to Mexico, Canada, Japan, and the United Kingdom. It is operated by an independent agency, the San Diego Regional Airport Authority. In addition, the city itself operates two general-aviation airports, Montgomery Field (MYF) and Brown Field (SDM).[191]

Numerous regional transportation projects have occurred in recent years to mitigate congestion in San Diego. Notable efforts are improvements to San Diego freeways, expansion of San Diego Airport, and doubling the capacity of the cruise ship terminal of the port. Freeway projects included expansion of Interstates 5 and 805 around “The Merge,” a rush-hour spot where the two freeways meet. Also, an expansion of Interstate 15 through the North County is underway with the addition of high-occupancy-vehicle (HOV) “managed lanes”. There is a tollway (The South Bay Expressway) connecting SR 54 and Otay Mesa, near the Mexican border. According to a 2007 assessment, 37 percent of streets in San Diego were in acceptable driving condition. The proposed budget fell $84.6 million short of bringing the city’s streets to an acceptable level.[192] Port expansions included a second cruise terminal on Broadway Pier which opened in 2010. Airport projects include expansion of Terminal 2, currently under construction and slated for completion in summer 2013.[193]

Sister cities

San Diego has 16 sister cities, as designated by Sister Cities International:[194][195]

See also


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