Facebook is a social networking website that users can join through networks organized by city, workplace, school, and region. People can also add friends and send them messages, and update their personal profiles to notify friends about themselves.

Mark Zuckerberg founded Facebook with fellow computer science major students and his roommates Dustin Moskovitz and Chris Hughes while he was a student at Harvard University. Website membership was initially limited to Harvard students, but was expanded to other colleges in the Boston area, the Ivy League, and Stanford University. It later expanded further to include any university student, then high school students, and, finally, to anyone aged 13 and over. The website currently has more than 250 million active users worldwide.

Facebook has met with some controversy over the past few years. It has been blocked intermittently in several countries including Syria, China and Iran, although Iran later unblocked Facebook in 2009. It has also been banned at many places of work to discourage employees from wasting time using the service. Privacy has also been an issue, and it has been compromised several times. Facebook is also facing several lawsuits from a number of Zuckerberg's former classmates, who claim that Facebook had stolen their source code and other intellectual property.

A February 2009 Compete.com study has ranked Facebook as the most used social network by worldwide monthly active users, followed by MySpace.   wikipedia

MySpace is a social networking website with an interactive, user-submitted network of friends, personal profiles, blogs, groups, photos, music, and videos for teenagers and adults internationally. Its headquarters are in Beverly Hills, California, USA, where it shares an office building with its immediate owner, Fox Interactive Media, which is owned by News Corporation. MySpace became the most popular social networking site in the United States in June 2006. According to comScore, MySpace was overtaken internationally by main competitor Facebook in April 2008, based on monthly unique visitors. MySpace employs 1,000 employees, after laying off 30% of its workforce in June 2009; the company does not disclose revenues or profits separately from News Corporation. The 100 millionth account was created on August 9, 2006, in the Netherlands.   wikipedia