Some Important Facts about Facebook

Facebook  is an American for-profit corporation and online social media and social networking service based in Menlo Park, California. 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 may 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, 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  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. Facebook classifies users from the ages of 13 to 18 as minors and therefore sets their profiles to share content with friends only.
History
2003–06: Thefacebook, Thiel investment, and name change
Zuckerberg wrote a program called "Facemash" on October 28, 2003 while attending Harvard University 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".
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"  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. 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 .

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, Dustin Moskovitz, Andrew McCollum, 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. 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.  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 . 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.