Facebook is a sosial networking website launched in February 2004 that is operated and privately owned by Facebook, Inc., with more than 500 million active users in July 2010. Users can add people as friends and send them messages, and update their personal profiles to notify friends about themselves. Additionally, users can join networks organized by workplace, school, or college. The website's name stems from the books given to students at the start of the academic year by university administrations in the US with the intention of helping students to get to know each other better. Facebook allows anyone who declares themselves to be aged 13 or older to become a member of the website.
Facebook was founded by  with his college roommates and fellow computer science students   and . The website's membership was initially limited by the founders to Harvard students, but was expanded to other colleges in the Boston area, the, and  It gradually added support for students at various other universities before opening to high school students, and, finally, to anyone aged 13 and over.
Facebook has met with some . It has been blocked intermittently in several countries including Pakistan, Syria, the , and Iran. It has also been banned at many places of work to discourage employees from wasting time using the service. Facebook's privacy has also been an issue, and the safety of their users has been compromised several times. Facebook settled a lawsuit regarding claims over source code and intellectual property. The site has also been involved in controversy over the sale of fans and friends.
A January 2009 study ranked Facebook as the most used social network by worldwide monthly active users, followed by MySpace.  put it 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?"