Facebook

Facebook (stylized as facebook) is a for-profit corporation and online social media and social networking service based in Menlo Park, California, United States. The Facebook website was launched on February 4, 2004, by Mark Zuckerberg, along with fellow Harvard College students and roommates, Eduardo Saverin, Andrew McCollum, Dustin Moskovitz, and Chris Hughes.

The founders had initially limited the website's membership to Harvard students; however, later they expanded it to higher education institutions in the Boston area, the Ivy League schools, and Stanford University. Facebook gradually added support for students at various other universities, and eventually to high school students as well. Since 2006, anyone age 13 and older has been allowed to become a registered user of Facebook, though variations exist in the minimum age requirement, depending on applicable local laws. The Facebook name comes from the face book directories often given to United States university students.

Facebook can be accessed by a large range of desktops, laptops, tablet computers, and smartphones over the Internet and mobile networks. After registering to use the site, users can create a user profile indicating their name, occupation, schools attended and so on. Users can add other users as "friends", exchange messages, post status updates and digital photos, share digital videos and links, use various software applications ("apps"), and receive notifications when others update their profiles or make posts. Additionally, users may join common-interest user groups organized by workplace, school, hobbies or other topics, and categorize their friends into lists such as "People From Work" or "Close Friends". In groups, editors can pin posts to top. Additionally, users can complain about or block unpleasant people. Because of the large volume of data that users submit to the service, Facebook has come under scrutiny for its privacy policies. Facebook makes most of its revenue from advertisements which appear onscreen.

Facebook, Inc. held its initial public offering (IPO) in February 2012, and began selling stock to the public three months later, reaching an original peak market capitalization of $104 billion. On July 13, 2015, Facebook became the fastest company in the Standard & Poor's 500 Index to reach a market cap of $250 billion. Facebook has more than 1.65 billion monthly active users as of March 31, 2016. As of April 2016, Facebook was the most popular social networking site in the world, based on the number of active user accounts.

2003–2006: Thefacebook, Thiel investment, and name change
Zuckerberg wrote a program called "Facemash" on October 28, 2003 while attending Harvard University as a sophomore (second year student). 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".

To accomplish this, Zuckerberg hacked into protected areas of Harvard's computer network and copied private dormitory ID images. Harvard did not have a student "face book" (a directory with photos and basic information) at the time, although individual houses had been issuing their own paper facebooks since the mid-1980s, and Harvard's longtime Freshman Yearbook was colloquially referred to as the "Freshman Facebook". Facemash attracted 450 visitors and 22,000 photo-views in its first four hours online.

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. Zuckerberg expanded on this initial project that semester by creating a social study tool ahead of an art history final exam. He uploaded 500 Augustan images to a website, each of which was featured with a corresponding comments section. He shared the site with his classmates, and people started sharing notes.



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

Six days after the site launched, Harvard seniors Cameron Winklevoss, Tyler Winklevoss, and Divya Narendra accused Zuckerberg of intentionally misleading them into believing that he would help them build a social network called HarvardConnection.com. They claimed that he was instead using their ideas to build a competing product. The three complained to The Harvard Crimson and the newspaper began an investigation. They later filed a lawsuit against Zuckerberg, subsequently settling in 2008 for 1.2 million shares (worth $300 million at Facebook's IPO).

Membership was initially restricted to students of Harvard College; within the first month, more than half the undergraduates at Harvard were registered on the service. Eduardo Saverin (business aspects), Dustin Moskovitz (programmer), Andrew McCollum (graphic artist), and Chris Hughes joined Zuckerberg to help promote the website. In March 2004, Facebook expanded to the universities of Columbia, Stanford, and Yale. It later opened to all Ivy League colleges, Boston University, New York University, MIT, and gradually most universities in the United States and Canada.

In mid-2004, entrepreneur Sean Parker—an informal advisor to Zuckerberg—became the company's president. In June 2004, Facebook moved its operations base to Palo Alto, California. It received its first investment later that month from PayPal co-founder Peter Thiel. In 2005, the company dropped "the" from its name after purchasing the domain name facebook.com for US$200,000. The domain facebook.com belonged to AboutFace Corporation before the purchase. This website last appeared on April 8, 2005; from April 10, 2005 to August 4, 2005, this domain gave a 403 error.



In May 2005, Accel Partners invested $12.7 million in Facebook, and Jim Breyer added $1 million of his own money. A high-school version of the site was launched in September 2005, which Zuckerberg called the next logical step. (At the time, high-school networks required an invitation to join.) Facebook also expanded membership eligibility to employees of several companies, including Apple Inc. and Microsoft.

2006–2012: public access, Microsoft alliance and rapid growth
On September 26, 2006, Facebook was opened to everyone at least 13 years old with a valid email address.

In late 2007, Facebook had 100,000 business pages (pages which allowed companies to promote themselves and attract customers). These started as group pages, but a new concept called company pages was planned. Pages began rolling out for businesses in May 2009.

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. Microsoft's purchase included rights to place international advertisements on the social networking site.

In October 2008, Facebook announced that it would set up its international headquarters in Dublin, Ireland. Almost a year later, in September 2009, Facebook said that it had turned cash-flow positive for the first time.

A January 2009 Compete.com study ranked Facebook the most used social networking service by worldwide monthly active users. 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?"

Traffic to Facebook increased steadily after 2009. The company announced 500 million users in July 2010 making it the largest online social network in the world at the time. According to the company's data, half of the site's membership use Facebook daily, for an average of 34 minutes, while 150 million users access the site by mobile. A company representative called the milestone a "quiet revolution."

In November 2010, based on SecondMarket Inc. (an exchange for privately held companies' shares), Facebook's value was $41 billion. The company had slightly surpassed eBay to become the third largest American web company after Google and Amazon.com.



In early 2011, Facebook announced plans to move its headquarters to the former Sun Microsystems campus in Menlo Park, California. In March 2011, it was reported that Facebook was removing approximately 20,000 profiles offline every day for violations such as spam, graphic content, and underage use, as part of its efforts to boost cyber security.

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 tracked by DoubleClick. According to a Nielsen Media Research study, released in December 2011, Facebook had become the second-most accessed website in the U.S. behind Google.

2012–2013: IPO, lawsuits and one-billionth user
Facebook eventually filed for an initial public offering on February 1, 2012. Facebook held an initial public offering on May 17, 2012, negotiating a share price of US$38. The company was valued at $104 billion, the largest valuation to date for a newly listed public company.

Facebook Inc. began selling stock to the public and trading on the NASDAQ on May 18, 2012. Based on its 2012 income of $5 billion, Facebook joined the Fortune 500 list for the first time in May 2013, ranked in position 462.

Facebook filed their S1 document with the Securities and Exchange Commission on February 1, 2012. The company applied for a $5 billion IPO, one of the biggest offerings in the history of technology. The IPO raised $16 billion, making it the third-largest in U.S. history.

The shares began trading on May 18; the stock struggled to stay above the IPO price for most of the day, but set a record for the trading volume of an IPO (460 million shares). The first day of trading was marred by technical glitches that prevented orders from going through; only the technical problems and artificial support from underwriters prevented the stock price from falling below the IPO price on the day.

In March 2012, Facebook announced App Center, a store selling applications that operate via the site. The store was to be available on iPhones, Android devices, and mobile web users.



On May 22, 2012, the Yahoo! Finance website reported that Facebook's lead underwriters, Morgan Stanley (MS), JP Morgan (JPM), and Goldman Sachs (GS), cut their earnings forecasts for the company in the middle of the IPO process. The stock had begun its freefall by this time, 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 stock price's decline. Securities and Exchange Commission Chairman Mary Schapiro, and Financial Industry Regulatory Authority (FINRA) Chairman Rick Ketchum, called for a review of the circumstances surrounding the IPO.

Facebook's IPO was consequently investigated, and was compared to a pump and dump scheme. A class-action lawsuit was filed in May 2012 because of the trading glitches, which led to botched orders. Lawsuits were filed, alleging that an underwriter for Morgan Stanley selectively revealed adjusted earnings estimates to preferred clients.

The other underwriters (MS, JPM, GS), Facebook's CEO and board, and NASDAQ also faced litigation after numerous lawsuits were filed, while SEC and FINRA both launched investigations. It was believed that adjustments to earnings estimates were communicated to the underwriters by a Facebook financial officer, who used the information to cash out on their positions while leaving the general public with overpriced shares. By the end of May 2012, Facebook's stock lost over a quarter of its starting value, which led the Wall Street Journal to label the IPO a "fiasco".

Zuckerberg announced to the media at the start of October 2012 that Facebook had passed the monthly active users mark of one billion —Facebook defines active users as a logged-in member who visits the site, or accesses it through a third-party site connected to Facebook, at least once a month. Fake accounts were not mentioned in the announcement, but the company continued to remove them after it found that 8.7% of its users were not real in August 2012. The company's data also revealed 600 million mobile users, 140 billion friend connections since the inception of Facebook, and the median age of a user as 22 years.

2013–present: site developments, A4AI and 10th anniversary
On January 15, 2013, Facebook announced Facebook Graph Search, which provides users with a "precise answer," rather than a link to an answer by leveraging the data present on its site. Facebook emphasized that the feature would be "privacy-aware," returning only results from content already shared with the user.

The company became the subject of a lawsuit by Rembrandt Social Media in February 2013, for patents involving the "Like" button. On April 3, 2013, Facebook unveiled Facebook Home, a user-interface layer for Android devices offering greater integration with the site. HTC announced the HTC First, a smartphone with Home pre-loaded.

On April 15, 2013, Facebook announced an alliance across 19 states with the National Association of Attorneys General, to provide teenagers and parents with information on tools to manage social networking profiles. On April 19, 2013, Facebook officially modified 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.

Following a campaign by 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 that caused withdrawal of advertising from the site 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". It decided to take action on May 29, 2013, after it "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."

On June 12, 2013, Facebook 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 topic. 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 local government area of the company's headquarters, 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. It noted the wages were "the equivalent of $168,000 a year, and more than 50% higher than the next-highest county, New York County (better known as Manhattan), at $2,107 a week, or roughly $110,000 a year."

Russian internet firm Mail.Ru sold its Facebook shares for US$525 million on September 5, 2013, following its initial $200 million investment in 2009. Partly owned by Russia's richest man, Alisher Usmanovhe, the firm owned a total of 14.2 million remaining shares prior to the sale. In the same month, the Chinese government announced that it will lift the ban on Facebook in the Shanghai Free Trade Zone "to welcome foreign companies to invest and to let foreigners live and work happily in the free-trade zone." Facebook was first blocked in China in 2009.

Facebook was announced as a member of The Alliance for Affordable Internet (A4AI) in October 2013, when the A4AI was launched. The A4AI is a coalition of public and private organisations that includes Google, Intel and Microsoft. Led by Sir Tim Berners-Lee, the A4AI seeks to make Internet access more affordable so that access is broadened in the developing world, where only 31% of people are online. Google will help to decrease Internet access prices so that they fall below the UN Broadband Commission's worldwide target of 5% of monthly income.

A Reuters report, published on December 11, 2013, stated that Standard & Poor's announced the placement of Facebook on its S&P 500 index "after the close of trading on December 20." Facebook announced Q4 2013 earnings of $523 million (20 cents per share), an increase of $64 million from the previous year, as well as 945 million mobile users.

By January 2014, Facebook's market capitalization had risen to over $134 billion. At the end of January 2014, 1.23 billion users were active on the website every month.

The company celebrated its 10th anniversary during the week of February 3, 2014. In each of the first three months of 2014, over one billion users logged into their Facebook account on a mobile device.

In February 2014, Facebook announced that it would be buying mobile messaging company Whatsapp for US$19 billion in cash and stock. In June 2014, Facebook announced the acquisition of Pryte, a Finnish mobile data-plan firm that aims to make it easier for mobile phone users in underdeveloped parts of the world to use wireless Internet apps.

At the start of July 2014, Facebook announced the acquisition of LiveRail, a San Francisco, California-based online video advertising company. LiveRail's technology facilitates the sale of video inventory across different devices. The terms of the deal were undisclosed, but TechCrunch reported that Facebook paid between US$400 million and $500 million. As part of the company's second quarter results, Facebook announced in late July 2014 that mobile accounted for 62% of its advertising revenue, which is an increase of 21% from the previous year.

Alongside other American technology figures like Jeff Bezos and Tim Cook, Zuckerberg hosted visiting Chinese politician Lu Wei, known as the "Internet czar" for his influence in the enforcement of China's online policy, at Facebook's headquarters on December 8, 2014. The meeting occurred after Zuckerberg participated in a Q&A session at Tsinghua University in Beijing, China, on October 23, 2014, where he attempted to converse in Mandarin—although Facebook is banned in China, Zuckerberg is highly regarded among the people and was at the university to help fuel the nation's burgeoning entrepreneur sector. A book of Chinese president Xi Xinping found on Zuckerberg's office desk attracted a great deal of attention in the media, after the Facebook founder explained to Lu, "I want them [Facebook staff] to understand socialism with Chinese characteristics."

Zuckerberg fielded questions during a live Q&A session at the company's headquarters in Menlo Park on December 11, 2014. The question of whether the platform would adopt a dislike button was raised again, and Zuckerberg said, "We're [Facebook] thinking about it [dislike button] … It's an interesting question," and said that he likes the idea of Facebook users being able to express a greater variety of emotions. In October 2015, Zuckerberg said that instead of creating a dislike button, Facebook is testing emoji reactions as an alternative to the 'like' button. On February 24, 2016, Facebook launched Facebook Reactions, which allows users to respond to posts with multiple reactions in addition to "liking" it.

As of January 21, 2015, Facebook's algorithm is programmed to filter out false or misleading content, such as fake news stories and hoaxes, and will be supported by users who select the option to flag a story as "purposefully fake or deceitful news." According to Reuters, such content is "being spread like a wildfire" on the social media platform. Facebook maintained that "satirical" content, "intended to be humorous, or content that is clearly labeled as satire," will be taken into account and should not be intercepted. The algorithm, however, has been accused of maintaining a "filter bubble", where both material the user disagrees with and posts with a low level of likes, will also not be seen. In 2015 November, Zuckerberg prolonged period of paternity leave from 4 weeks to 4 months.

On April 12, 2016, Zuckerberg revealed a decade-long plan for Facebook in a keynote address. His speech outlined his vision, which was centered around three main pillars: artificial intelligence, increased connectivity around the world and virtual and augmented reality. He also announced a new Facebook Messenger platform, which will have developers creating bots that are able to engage in automatic interactions with customers. In June 2016 Facebook announced Deep Text, a natural language processing AI which will learn user intent and context in 20 languages.

On May 31, 2016, Facebook, along with Google, Microsoft, and Twitter, jointly agreed to a European Union code of conduct obligating them to review "[the] majority of valid notifications for removal of illegal hate speech" posted on their services within 24 hours.

Facebook introduced 360-degree photo to posts on June 9, 2016. If one has a compatible Samsung phone, Facebook will display a dedicated "view in VR" button, then users will have to insert the phone into their Gear VR headsets to watch the photo in a more immersive style.

In July 2016, a $US 1 billion lawsuit was filed against the company alleging that it permitted the Hamas group to use it to perform assaults that ended the lives of 4 people. Facebook released the blueprints of Surround 360 camera on GitHub under Open-source license.

In September 2016, it won an Emmy for it's Visual animated short "Henry".

On September 30, Facebook launched "Messenger Day" in Poland, a competitor to Snapchat, where users can share filtered photos and videos that disappear in 24 hours.

Management
The ownership percentages of the company,, were:
 * Mark Zuckerberg: 28%
 * Accel Partners: 10%
 * Dustin Moskovitz: 6%
 * Eduardo Saverin: 5%
 * Sean Parker: 4%
 * Peter Thiel: 3%
 * Greylock Partners: between 1 and 2%
 * Meritech Capital Partners: between 1 and 2% each
 * Microsoft: 1.3%
 * Li Ka-shing: 0.8%
 * 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. 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.

Key management personnel consist of: Chris Cox (Chief Product Officer), Sandberg (COO), and Zuckerberg (Chairman and CEO). Mike Vernal is considered to be the company's top engineer. , Facebook has over 7,000 employees, and offices in 15 countries. Other managers include chief financial officer David Wehner and public relations head Elliot Schrage.

Facebook was named the 5th best company to work for in 2014 by company-review site Glassdoor as part of its sixth annual Employees' Choice Awards. The website stated that 93% of Facebook employees would recommend the company to a friend.

Revenue
Most of Facebook's revenue comes from advertising. Facebook generally has a lower clickthrough rate (CTR) for advertisements than most major websites. 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, 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), Facebook's users click on advertisements an average of 0.04% of the time (400 clicks for every one million pages).

Sarah Smith, who was Facebook's Online Sales Operations Manager until 2012, reported 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.

The cause of Facebook's low CTR has been attributed to younger users enabling ad blocking software and their adeptness at ignoring advertising messages, as well as the site's primary purpose being social communication rather than content viewing. According to digital consultancy iStrategy Labs in mid-January 2014, three million fewer users aged between 13 and 17 years were present on Facebook's Social Advertising platform compared to 2011. However, Time writer and reporter Christopher Matthews stated in the wake of the iStrategy Labs results:

A big part of Facebook's pitch is that it has so much information about its users that it can more effectively target ads to those who will be responsive to the content. If Facebook can prove that theory to be true, then it may not worry so much about losing its cool cachet.

In December 2014, a report from Frank N. Magid and Associates found that the percentage of teens aged 13 to 17 who used Facebook fell to 88% in 2014, down from 94% in 2013 and 95% in 2012.

Zuckerberg, alongside other Facebook executives, have questioned the data in such reports; although, a former Facebook senior employee has commented: "Mark [Zuckerberg] is very willing to recognize the strengths in other products and the flaws in Facebook."

On pages for brands and products, however, some companies have reported CTR as high as 6.49% for Wall posts. 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.

The company released its own set of revenue data at the end of January 2014 and claimed: Revenues of US$2.59 billion were generated for the three months ending December 31, 2013; earnings per share were 31 cents; revenues of US$7.87 billion were made for the entirety of 2013; and Facebook's annual profit for 2013 was US$1.5 billion. During the same time, independent market research firm eMarketer released data in which Facebook accounted for 5.7 per cent of all global digital ad revenues in 2013 (Google's share was 32.4 per cent). Revenue for the June 2014 quarter rose to $2.68 billion, an increase of 67 per cent over the second quarter of 2013. Mobile advertising revenue accounted for around 62 per cent of advertising revenue, an increase of approximately 41 per cent over the comparable quarter of the previous year.

Number of advertisers
In February 2015, Facebook announced that it had reached two million active advertisers with most of the gain coming from small businesses. An active advertiser is an advertiser that has advertised on the Facebook platform in the last 28 days. In March 2016, Facebook announced that it reached three million active advertisers with more than 70% from outside the US.

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.

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

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.

In 2010, Facebook opened its fourth office, in Hyderabad  and the first in Asia.

Facebook, which in 2010 had more than 750 million active users globally including over 23 million in India, announced that its Hyderabad center would house online advertising and developer support teams and provide round-the-clock, multilingual support to the social networking site's users and advertisers globally. With this, Facebook joins other giants like Google, Microsoft, Oracle, Dell, IBM and Computer Associates that have already set up shop. In Hyderabad, it is registered as 'Facebook India Online Services Pvt Ltd'.

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, which would supplement its operations in California, Dublin in Ireland as well as at Austin, Texas.

A custom-built data center with substantially reduced ("38% less") power consumption compared to existing Facebook data centers opened in April 2011 in Prineville, Oregon. In April 2012, Facebook opened a second data center in Forest City, North Carolina, US. In June 2013, Facebook opened a third data center in Luleå, Sweden. In November 2014, Facebook opened a fourth data center in Altoona, Iowa, US.

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. 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 analogue VK has around 34 million.

The functioning of a woodwork facility on the Menlo Park campus was announced at the end of August 2013. The facility, opened in June 2013, provides equipment, safety courses and woodwork learning course, while employees are required to purchase materials at the in-house store. A Facebook spokesperson explained that the intention of the facility is to encourage employees to think in an innovative manner because of the different environment, and also serves as an attractive perk for prospective employees.

Open source contributions
Facebook is both a consumer of and contributor to free and open source software. Facebook's contributions include: HipHop for PHP, Fair scheduler in Apache Hadoop, Apache Hive, Apache Cassandra, and the Open Compute Project.

Facebook also contributes to other opensource projects such as Oracle's MySQL database engine.

Technical aspects
The website's primary color is blue as Zuckerberg is red-green colorblind, a realization that occurred after a test undertaken around 2007; he explained in 2010: "blue is the richest color for me—I can see all of blue." 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%.

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.

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).

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 number 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.

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.

On March 20, 2014 Facebook announced a new open source programming language called Hack. Prior to public release, a large portion of Facebook was already running and "battle tested" using the new language.

Facebook uses the Momentum platform from Message Systems to deliver the enormous volume of emails it sends to its users every day.

History
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. After initially giving users a choice to switch, Facebook began migrating all users to the new version starting in September 2008. On December 11, 2008, it was announced that Facebook was testing a simpler signup process.

Chat

 * Facebook Chat was added April 6, 2008. It is a Comet-based instant messaging application which allows users to communicate with other Facebook users in a way similar in functionality to instant messaging software.

Gifts

 * 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.

Marketplace

 * On May 14, 2007, Facebook launched Marketplace, which lets users post free classified ads. 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.

Messaging

 * 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 messagesincluding just friends, friends of friends, or from anyone.  Email service was terminated in 2014 because of low uptake. Aside from the Facebook website, messages can also be accessed through the site's mobile apps, or a dedicated Facebook Messenger app.

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.

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.

Video viewing

 * In September 2014, Facebook announced that it delivers 1 billion video views per day and that it would begin showing everyone view counts on publicly posted videos from users, Pages, and public figures. It also confirmed that it is recommending additional videos to users after they have watched a video. Sixty-five percent of Facebook's video views are coming from mobile where Facebook's user base is shifting, and views grew 50 percent from May to July, in part thanks to the viral ALS Ice Bucket Challenge finding a home on Facebook.

Tor hidden service

 * In October 2014, Facebook announced that users could now connect to the website through a Tor hidden service using the privacy-protecting Tor browser and encrypted using SSL. Announcing the feature, Alec Muffett said "Facebook's onion address provides a way to access Facebook through Tor without losing the cryptographic protections provided by the Tor cloud. […] it provides end-to-end communication, from your browser directly into a Facebook datacentre." Its URL address facebookcorewwwi.onion is a backronym, which stands for Facebook's Core WWW Infrastructure.

User profile/personal timeline
The format of individual user pages was revamped in late 2011 and became known as either a profile or personal timeline since that change. Users can create profiles with photos and images, lists of personal interests, contact information, memorable life events, and other personal information, such as employment status. Users can communicate with friends and other users through private or public messages, as well as a chat feature, and share content that includes website URLs, images, and video content. A 2012 Pew Internet and American Life study identified that between 20 and 30 percent of Facebook users are "power users" who frequently link, poke, post and tag themselves and others.

In 2007, Facebook launched Facebook Pages (also called "Fan Pages" by users) to allow "users to interact and affiliate with businesses and organizations in the same way they interact with other Facebook user profiles". On November 6, 2007, more than 100,000 Facebook pages were launched.

In July 2012, Facebook added a same-sex marriage icon to its timeline feature. On February 14, 2014, Facebook expanded the options for user's gender setting, adding a custom input field that allows users to choose from a wide range of gender identities. Users can also set which set of gender-specific pronouns are used in reference to them throughout the site. The change occurs after Nepal's first openly gay politician Sunil Babu Pant sent a letter to Zuckerberg in early 2012 to request the addition of an "Other" gender option for Facebook users; Facebook's official statement on the issue: "People can already opt out of showing their sex on their profile. We're constantly innovating on our products and features and we welcome input from everyone as we explore ways to improve the Facebook experience."

On June 13, 2009, Facebook introduced a "Usernames" feature, whereby pages can be linked with simpler URLs such as  instead of. 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 Android, iOS, webOS, and Firefox OS. Nokia and Research In Motion both provide Facebook applications for their own mobile devices. As of January 2015, 745 million active users access Facebook through mobile devices every day.

In May 2014, Facebook introduced a feature to allow users to ask for information not disclosed by other users on their profiles. If a user does not provide key information, such as location, hometown, or relationship status, other users can use a new 'ask' button to send a message asking about that item to the user in a single click.

News Feed
On September 6, 2006, 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. 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. 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).

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.

On February 23, 2010, Facebook was granted a patent 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. The patent may encourage Facebook to pursue action against websites that violate its patent, which may potentially include websites such as Twitter.

One of the most popular applications on Facebook is the Photos application, where users can upload albums and photos. Facebook allows users to upload an unlimited number of photos, compared with other image hosting services such as Photobucket and Flickr, 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.

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 she has been tagged, and provides a link to see the photo.

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. Since the launch of the App Center, Facebook has seen 150M monthly users with 2.4 times the installation of apps.

The sorting and display of stories in a user's News Feed is governed by the EdgeRank algorithm.

On May 13, 2015 Facebook in association with major news portals launched a program "Instant Articles" to provide rich news experience. Instant articles provides users, access to articles on Facebook news feed without leaving the site.

According to the technology news web site Gizmodo on May 9, 2016, Facebook curators routinely suppress or promote news that is deemed to meet a political agenda. For example, articles about Black Lives Matter would be listed even if they did not meet the trending criteria of News Feed. Likewise positive news about conservative political figures were regularly excised from Facebook pages.

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 – that enables participating Internet websites to display a similar like button.

The sheriff of Hampton, Virginia, US fired employees who liked the Facebook page of an adversary, and a federal appeals court in Virginia ruled that the US Constitution protects the rights of US citizens to like any Facebook page of their choosing. US Circuit Judge William Traxler likened the practice to displaying a "political sign in one's front yard." Additionally, the United States Court of Appeals for the Second Circuit upheld a National Labor Relations Board decision which found that one employee's "liking" another employee's negative comments about their employer deserved protection under the National Labor Relations Act, alerting employers to proceed with caution when disciplining employees for Facebook activity.

Following a lengthy period of calls from the public to include a dislike button on the Facebook interface, Zuckerberg explained in a Q&A session on December 11, 2014 that his hesitance was due to a concern about a tone of negativity on the platform, whereby users could "shame" others, and he offered the comment option for situations where people were unwilling to use the like function. However, he said, "We're [Facebook] thinking about it [dislike button] … It's an interesting question," and said that he likes the idea of Facebook users being able to express a greater variety of emotions.

Following
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 him or her as a friend. In conjunction, Facebook also introduced a system in February 2012 to verify the identity of certain accounts.

In December 2012, Facebook announced that because of user confusion surrounding its function, the Subscribe button would be re-labeled as a "Follow" buttonmaking it more similar to other social networks with similar functions.

Comparison with Myspace
The media often compares Facebook to Myspace, but one significant difference between the two Web sites is the level of customization. Another difference is Facebook's requirement that users give their true identity, a demand that MySpace does not make. MySpace allows users to decorate their profiles using HTML and Cascading Style Sheets (CSS), while Facebook allows only plain text. 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; Pokes, which allows users to send a virtual "poke" to each other (a notification then tells a user that he or she has been poked); Photos, that allows users to upload albums and photos; and Status, which allows users to inform their friends of their whereabouts and actions. Facebook also allows users to tag various people in photographs. 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. Facebook also differs from Myspace in the form of advertising used. Facebook uses advertising in the form of banner ads, referral marketing, and games. Myspace, on the other hand, uses Google and AdSense. There is also a difference in the userbase of each site. MySpace, initially, was much more popular with high school students, while Facebook was more popular among college students. A study by the American firm Nielsen Claritas showed that Facebook users are more inclined to use other professional networking sites, such as LinkedIn, than Myspace users.

Privacy
Facebook enables users to choose their own privacy settings and choose who can see specific parts of their profile. The website is free to its users and generates revenue from advertising, such as banner ads. 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.

On November 6, 2007, Facebook launched Facebook Beacon, which was a part of Facebook's advertisement system until it was discontinued in 2009. Its purpose was to allow targeted advertisements and allowing users to share their activities with their friends.

In 2010, Facebook's security team began expanding its efforts to reduce the risks to users' privacy, but privacy concerns remain.

Since 2010, among other social media services, the National Security Agency has been taking publicly posted profile information from users Facebook profiles to discover who they interact with.

On November 29, 2011, Facebook settled Federal Trade Commission charges that it deceived consumers by failing to keep privacy promises.

In August 2013 High-Tech Bridge published a study showing that links included in Facebook messaging service messages were being accessed by Facebook. In January 2014 two users filed a lawsuit against Facebook alleging that their privacy had been violated by this practice.

Facebook Bug Bounty Program
On July 29, 2011, Facebook announced its Bug Bounty Program in which security researchers will be paid a minimum of $500 for reporting security holes on Facebook website. Facebook's Whitehat page for security researchers says: "If you give us a reasonable time to respond to your report before making any information public and make a good faith effort to avoid privacy violations, destruction of data, and interruption or degradation of our service during your research, we will not bring any lawsuit against you or ask law enforcement to investigate you."



Facebook started paying researchers who find and report security bugs by issuing them custom branded "White Hat" debit cards that can be reloaded with funds each time the researchers discover new flaws. "Researchers who find bugs and security improvements are rare, and we value them and have to find ways to reward them," Ryan McGeehan, former manager of Facebook's security response team, told CNET in an interview. "Having this exclusive black card is another way to recognize them. They can show up at a conference and show this card and say 'I did special work for Facebook.'"

India, which has the second largest number of bug hunters in the world, tops the Facebook Bug Bounty Program with the largest number of valid bugs. "Researchers in Russia earned the highest amount per report in 2013, receiving an average of $3,961 for 38 bugs. India contributed the largest number of valid bugs at 136, with an average reward of $1,353. The U.S. reported 92 issues and averaged $2,272 in rewards. Brazil and the UK were third and fourth by volume, with 53 bugs and 40 bugs, respectively, and average rewards of $3,792 and $2,950", Facebook quoted in a post.

Reception
According to comScore, Facebook is the leading social networking site based on monthly unique visitors, having overtaken main competitor MySpace in April 2008. ComScore reports that Facebook attracted 130 million unique visitors in May 2010, an increase of 8.6 million people. According to third-party web analytics providers, Alexa and SimilarWeb, Facebook is ranked second and first globally respectively, it is the highest-read social network on the Web, with over 20 billion visitors per month, as of 2015. SimilarWeb, Quantcast and Compete.com all rank the website 2nd in the U.S. in traffic. The website is the most popular for uploading photos, with 50 billion uploaded cumulatively. 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.

Facebook is the most popular social networking site in several English-speaking countries, including Canada, the United Kingdom, and the United States. However, Facebook still receives limited adoption in countries such as Japan, where domestically created social networks are still largely preferred. 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). Some of the top competitors were listed in 2007 by Mashable.

The website has won awards such as placement into the "Top 100 Classic Websites" by PC Magazine in 2007, and winning the "People's Voice Award" from the Webby Awards in 2008. In a 2006 study conducted by Student Monitor, a 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.

In 2010, Facebook won the Crunchie "Best Overall Startup Or Product" for the third year in a row and was recognized as one of the "Hottest Silicon Valley Companies" by Lead411. 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.

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. 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. Employers 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.

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. In 2008, Collins English Dictionary declared "Facebook" as its new Word of the Year. 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.

In early 2010, Openbook was established, an avowed parody (and privacy advocacy) website 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 referer 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".

In May 2014, the countries with the most Facebook users were:
 * United States with 151.8 million members
 * India with 108.9 million members
 * Brazil with 70.5 million members
 * Indonesia with 60.3 million members
 * Mexico with 44.4 million members

Facebook's popularity throughout the world (especially as a tool for political movements or procrastination) has led to some countries and employers blocking access to the site.

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

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. In January 2016, Facebook Messenger hits 800 million users.

Electricity usage
On April 21, 2011, Greenpeace released a report showing that of the top ten big brands in cloud computing, Facebook was most reliant on coal for electricity for its data centers. At the time, data centers consumed up to 2% of all global electricity and this amount was projected to increase. Phil Radford of Greenpeace said "we are concerned that this new explosion in electricity use could lock us into old, polluting energy sources instead of the clean energy available today." On December 15, 2011, Greenpeace and Facebook announced together that Facebook would shift to use clean and renewable energy to power its own operations. Marcy Scott Lynn, of Facebook's sustainability program, said it looked forward "to a day when our primary energy sources are clean and renewable" and that the company is "working with Greenpeace and others to help bring that day closer."

Google
In May 2011 emails were sent to journalists and bloggers making critical allegations about Google's privacy policies; however it was later discovered that PR giant Burson-Marsteller was paid for the emails by Facebook.

Users violating minimum age requirements
A 2011 study in the online journal First Monday, 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 is in compliance with a United States law, the 1998 Children's Online Privacy Protection Act, which requires minors aged 13 or younger to gain explicit parental consent to access commercial websites. In other jurisdictions where a similar law sets a lower minimum age, Facebook enforces the lower age. Of the 1,007 households surveyed for the study, 76% of parents reported that their child joined Facebook at an age younger than 13, the minimum age in the site's terms of service. The study also reported that Facebook removes roughly 20,000 users each day for violating its minimum age policy. 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 merely a recommendation, or thought the signup age was 16 or 18, and not 13.

Accounts hacked in Bangalore, India
In November 2011, several Facebook users in Bangalore, India reported that their accounts had been hacked and their profile pictures replaced with pornographic images. For more than a week, users' news feeds were spammed with pornographic, violent and sexual content, 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.

Unauthorized wall posting bug
On August 19, 2013, it was reported that a Facebook user from Yatta, West Bank Khalil Shreateh had found a bug that allowed him to post material to other users' Facebook Walls. Users are not supposed to have the ability to post material to the Facebook Walls of other users unless they are approved friends of those users that they have posted material to. To prove that he was telling the truth, Shreateh posted material to Sarah Goodin's wall, a friend of Facebook CEO Mark Zuckerberg. Following this, Shreateh contacted Facebook's security team with the proof that his bug was real, explaining in detail what was going on. Facebook has a bounty program in which it compensates people a US$500 fee for reporting bugs instead of using them to their advantage or selling them on the black market. However, it was reported that instead of fixing the bug and paying Shreateh the fee, Facebook originally told him that "this was not a bug" and dismissed him. Shreateh then tried a second time to inform Facebook, but they dismissed him yet again. On the third try, Shreateh used the bug to post a message to Mark Zuckerberg's Wall, stating "Sorry for breaking your privacy … but a couple of days ago, I found a serious Facebook exploit" and that Facebook's security team was not taking him seriously. Within minutes, a security engineer contacted Shreateh, questioned him on how he performed the move and ultimately acknowledged that it was a bug in the system. Facebook temporarily suspended Shreateh's account and fixed the bug after several days. Facebook refused to pay out the bounty to Shreateh, stating that by posting to Zuckerberg's account, Shreateh had violated one of their terms of service policies and therefore "could not be paid." Facebook also noted that in Shreateh's initial reports, he had failed to provide technical details for Facebook to act on the bug.

On August 22, 2013, Yahoo News reported that Marc Maiffret, a chief technology officer of the cybersecurity firm BeyondTrust, is prompting hackers to support in raising a $10,000 reward for Khalil Shreateh. On August 20, Maiffret stated that he had already raised $9,000 in his efforts, including the $2,000 he himself contributed. He and other hackers alike have denounced Facebook for refusing Shreateh compensation. Stated Maiffret, "He is sitting there in Palestine doing this research on a five-year-old laptop that looks like it is half broken. It's something that might help him out in a big way." Facebook representatives have since responded, "We will not change our practice of refusing to pay rewards to researchers who have tested vulnerabilities against real users." Facebook representatives also claimed they'd paid out over $1 million to individuals who have discovered bugs in the past.

Users quitting
A 2013 study examined the reasons users eventually quit the site. It found the most common reasons were privacy concerns (48%), 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.

iPhone 'Paper' app
Following the release of the Facebook iPhone app "Paper" at the beginning of February 2014, developer company FiftyThree sent a correspondence to the social media company regarding its own app, also entitled Paper and trademarked in 2012, asking Facebook to cease using an app name that they consider their own. In response, Facebook stated that it will continue to use the Paper title but conceded that it should have informed FiftyThree at an earlier point in time. FiftyThree articulated its desired outcome in a blog post: "There's a simple fix here. We think Facebook can apply the same degree of thought they put into the app into building a brand name of their own. An app about stories shouldn't start with someone else's story. Facebook should stop using our brand name."

Lane v. Facebook, Inc.
On March 2010, Judge Richard Seeborg issued an order approving the class settlement in Lane v. Facebook, Inc. This lawsuit charged that user's private information was being posted on Facebook without consent using Facebook's Beacon program.

User influence experiments
Academic and Facebook researchers have collaborated to test if the messages people see on Facebook can influence their behavior. For instance, in "A 61-Million-Person Experiment in Social Influence And Political Mobilization," during the 2010 elections, Facebook users were given the opportunity to "tell your friends you voted" by clicking on an "I voted" button. Users were 2% more likely to click the button if it was associated with friends who had already voted.

Much more controversially, a 2014 study of "Emotional Contagion Through Social Networks" manipulated the balance of positive and negative messages seen by 689,000 Facebook users. The researchers concluded that they had found "some of the first experimental evidence to support the controversial claims that emotions can spread throughout a network, [though] the effect sizes from the manipulations are small."

Unlike the "I voted" study, which had presumptively beneficial ends and raised few concerns, this study was criticized for both its ethics and methods/claims. As controversy about the study grew, Adam Kramer, a lead author of both studies and member of the Facebook data team, defended the work in a Facebook update. A few days later, Sheryl Sandburg, Facebook's COO, made a statement while traveling abroad. While at an Indian Chambers of Commerce event in New Delhi she stated that "This was part of ongoing research companies do to test different products, and that was what it was. It was poorly communicated and for that communication we apologize. We never meant to upset you."

Shortly thereafter, on July 3, 2014, USA Today reported that the privacy watchdog group Electronic Privacy Information Center (EPIC) had filed a formal complaint with the Federal Trade claiming that Facebook had broken the law when it conducted the study on the emotions of its users without their knowledge or consent. In its complaint, EPIC alleged that Facebook had deceived it users by secretly conducting a psychological experiment on their emotions: "At the time of the experiment, Facebook did not state in the Data Use Policy that user data would be used for research purposes. Facebook also failed to inform users that their personal information would be shared with researchers."

Beyond the ethical concerns, other scholars criticized the methods and reporting of the study's findings. John Grohol, writing for Psych Central, argued that despite its title and claims of "emotional contagion," this study did not look at emotions at all. Instead, its authors used an application (called "Linguistic Inquiry and Word Count" or LIWC 2007) that simply counted positive and negative words in order to infer users' sentiments. He wrote that a shortcoming of the LIWC tool is that it does not understand negations. Hence, the tweet "I am not happy" would be scored as positive: "Since the LIWC 2007 ignores these subtle realities of informal human communication, so do the researchers." Grohol concluded that given these subtleties, the effect size of the findings are little more than a "statistical blip."

"Kramer et al. (2014) found a 0.07%—that's not 7 percent, that's 1/15th of one percent!!—decrease in negative words in people's status updates when the number of negative posts on their Facebook news feed decreased. Do you know how many words you'd have to read or write before you've written one less negative word due to this effect? Probably thousands."

The consequences of the controversy are pending (be it FTC or court proceedings) but it did prompt an "Editorial Expression of Concern" from its publisher, the Proceedings of the National Academy of Sciences, as well as an blog posting from OkCupid that "We experiment on human beings!" In September 2014, law professor James Grimmelmann argued that the actions of both companies were "illegal, immoral, and mood-altering" and filed notices with the Maryland Attorney General and Cornell Institutional Review Board.

In the UK, the study was also criticised by the British Psychological Society which said, in a letter to The Guardian, "There has undoubtedly been some degree of harm caused, with many individuals affected by increased levels of negative emotion, with consequent potential economic costs, increase in possible mental health problems and burden on health services. The so-called 'positive' manipulation is also potentially harmful."

Real-name policy controversy and compromise
Facebook has a real-name system policy for user profiles. The real-name policy stems from the position "that way, you always know who you're connecting with. This helps keep our community safe." Facebook's real-name system does not allow adopted names or pseudonyms, and in its enforcement has suspended accounts of legitimate users, until the user provides identification indicating the name. Facebook representatives have described these incidents as very rare. A user claimed responsibility via the anonymous Android and iOS app Secret for reporting "fake names" which caused user profiles to be suspended, specifically targeting the stage names of drag queens. On October 1, 2014, Chris Cox, Chief Product Officer at Facebook, offered an apology: "In the two weeks since the real-name policy issues surfaced, we've had the chance to hear from many of you in these communities and understand the policy more clearly as you experience it. We've also come to understand how painful this has been. We owe you a better service and a better experience using Facebook, and we're going to fix the way this policy gets handled so everyone affected here can go back to using Facebook as you were."

On December 15, 2015, Facebook announced in a press release that it would be providing a compromise to its real name policy after protests from groups such as the gay/lesbian community and abuse-victims. The site is developing a protocol that will allow members to provide specifics as to their "special circumstance" or "unique situation" with a request to use pseudonyms, subject to verification of their true identities. At that time, this was already being tested in the U.S. Product manager Todd Gage and vice president of global operations Justin Osofsky also promised a new method for reducing the number of members who must go through ID verification while ensuring the safety of others on Facebook. The fake name reporting procedure will also be modified, forcing anyone who makes such an allegation to provide specifics that would be investigated and giving the accused individual time to dispute the allegation.

"Free basics" controversy in India
In February 2016, TRAI ruled against differential data pricing for limited services from mobile phone operators effectively ending zero-rating platforms in India. Zero rating provides access to limited number of websites for no charge to the end user. Net-neutrality supporters from India(SaveTheInternet.in) brought out the negative implications of Facebook Free Basic program and spread awareness to the public. Facebook's Free Basics program was a collaboration with Reliance Communications to launch Free Basics in India. The TRAI ruling against differential pricing marked the end of Free Basics in India.

Earlier, Facebook had spent $44 million USD in advertising and it implored all of its Indian users to send an email to the Telecom Regulatory Authority to support its program. TRAI later asked Facebook to provide specific responses from the supporters of Free Basics

Safety Check bug
On March 27, 2016, following a bombing in Lahore, Pakistan, Facebook activated its "Safety Check" feature, which allows people to let friends and loved ones know they are okay following a crisis or natural disaster, to people who were never in danger, or even close to the Pakistan explosion. Some users as far as the US, UK and Egypt received notifications asking if they were okay.

U.S. federal tax examination
On July 6, 2016, the U.S. Department of Justice filed a petition in the U.S. District Court in San Francisco, asking for a court order to enforce an administrative summons issued to Facebook, Inc., under Internal Revenue Code section 7602, in connection with an Internal Revenue Service examination of Facebook's year 2010 U.S. Federal income tax return.

Support for terrorism lawsuit
In July 2016, a civil action for $1 billion in damages was filed in the United States District Court for the Southern District of New York on behalf of the victims and family members of four Israeli-Americans and one US citizen killed since June 2014 by Hamas terrorists who had used Facebook.The government of the United States has designated Hamas as a Foreign Terrorist Organization and the suit alleges that Facebook provided Hamas with "material support" in violation of US Anti-Terrorism laws.

Stalking
At least one adolescent accused of serial rape was described as using Facebook to make friends of his victims.

Media impact
In April 2011, Facebook launched a new portal for marketers and creative agencies to help them develop brand promotions on Facebook. 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 Blood, American Idol, and Top Gear. News and media outlets such as the Washington Post, Financial Times and ABC News 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.

Social impact
Facebook has affected the social life and activity of people in various ways. Facebook allows people using computers or mobile phones 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 has reunited lost family members and friends. It allows users to trade ideas, stay informed with local or global developments, and unite people with common interests and/or beliefs through open, closed and private groups and other pages.

Facebook's social impact has also changed how people communicate. Rather than having to reply to others through email, Facebook allows users to broadcast or share content to others, and thereby to engage others or be engaged with others' posts.

Facebook has been successful and more socially impactful than many other social media sites. David Kirkpatrick, technology journalist and author of The Facebook Effect, believes that Facebook is structured in a way that is not easily replaceable. He challenges users to consider how difficult it would be to move all the relationships and photos to an alternative. Facebook has let people participate in an atmosphere with the "over the backyard fence quality" of a small town, despite the move to larger cities. As per Pew Research Center survey, 44 percent of the overall population gets news through Facebook.

Emotional health impact
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.

According to professor of psychology Susan Krauss Whitbourne, although Facebook has an upside of friending people, there is also the downside of having someone unfriend or reject another person. Whitbourne refers to unfriended persons on Facebook as victims of estrangement. Unfriending someone is seldom a mutual decision and the person often does not know he has been unfriended.

Political impact


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). In August 2010, one of North Korea's official government websites and the official news agency of the country, Uriminzokkiri, joined Facebook.

During the Arab Spring many journalists made claims that Facebook played a major role in generating the 2011 Egyptian revolution. 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. According to Mashable, in Tunisia and Egpyt, Facebook became the primary tool for connecting all protesters and led the Egyptian government of Prime Minister Nazif to ban Facebook, Twitter and another websites on January 26 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 Bahrain uprising which started on February 14, 2011, Facebook was utilized by the Bahraini regime as well as regime loyalists to identify, capture and prosecute citizens involved in the protests. A 20-year-old girl named Ayat Al Qurmezi was identified as a protester using Facebook, taken from her home by masked commandos and put in prison.

In 2011, Facebook filed paperwork with the Federal Election Commission to form a political action committee under the name FB PAC. In an email to The Hill, a spokesman for Facebook said "Facebook Political Action Committee 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."

During the Syrian civil war, the YPG, a libertarian army for Rojava has recruited westerners through Facebook in its fight against ISIL. Dozens have joined its ranks for various reasons from religious to ideological. The Facebook page's name "The Lions of Rojava" comes from a Kurdish saying which translates as "A lion is a lion, whether it's a female or a male", reflecting the organisation's feminist ideology.

United States
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. Facebook users took part in debate groups organized around specific topics, register to vote, and message questions.

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. 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. A poll by CBS News, UWIRE and The Chronicle of Higher Education claimed to illustrate 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.

The new social media, such as Facebook and Twitter, made use first of the personal computer and the Internet, and after 2010 of the smart phones to connect hundreds of millions of people, especially those under age 35. By 2008, politicians and interest groups were experimenting with systematic use of social media to spread their message among much larger audiences than they had previously reached.

Facebook is having an impact on local government as well. Justin Smith, a Colorado sheriff uses Facebook to disseminate his ideas on matters relating to local, state, and national concerns. He also publicizes crimes, particularly those that his department solves. He has seven thousand followers on the social medium, considered a large number. Smith said that he rarely goes out in public "when I don't get feedback from folks. … Facebook is an interesting tool because I think it holds candidates and elected officials more accountable. Voters know where someone stands."

As American political strategists turn their attention to the 2016 presidential contest, they identify Facebook as an increasingly important advertising tool. Recent technical innovations have made possible more advanced divisions and subdivisions of the electorate. Most important, Facebook can now deliver video ads to small, highly targeted subsets. Television, by contrast, shows the same commercials to all viewers, and so cannot be precisely tailored.

Ban
In many countries the social networking sites and mobile apps have been blocked temporarily or permanently. In Bangladesh, the government has been blocking Facebook, WhatsApp, Tango, Viber and many other sites and apps since November 18, 2015.

In popular culture

 * American author Ben Mezrich published a book in July 2009 about Zuckerberg and the founding of Facebook, titled The Accidental Billionaires: The Founding of Facebook, A Tale of Sex, Money, Genius, and Betrayal.
 * The Social Network, a drama film directed by David Fincher and adapted from Mezrich's book, was released October 1, 2010. People portrayed in the movie, including Zuckerberg, have criticized its accuracy. However a search of IMDB will reveal this to be a movie produced as standard entertainment.
 * In response to the Everybody Draw Mohammed Day controversy and the banning of the website in Pakistan, an Islamic version of the website was created, called MillatFacebook.
 * "You Have 0 Friends", an April 2010 episode of the American animated comedy series, South Park, explicitly parodied Facebook.
 * At age 102, Ivy Bean of Bradford, England joined Facebook in 2008, making her one of the oldest people ever on Facebook. At the time of her death in July 2010, she had 4,962 friends on Facebook and more than 56,000 followers on Twitter.
 * On May 16, 2011, an Israeli couple named their daughter after the Facebook "like" feature.
 * In July 2014, Shakira became the first celebrity to cross over 100 million likes, Cristiano Ronaldo is the second to reach 100 million likes, ahead of Rihanna and Eminem, who had 98 million and 89 million likes respectively. Mark Zuckerberg posted a congratulatory message on the artist's wall.