Facebook is a social networking website that launched on February 4 2004. The website is free to use and allows users to join one or more networks, such as a school, place of employment, or geographic region in order to easily connect with other people in the same network. The name of the website refers to the paper facebooks that depict members of a campus community that some American colleges and preparatory schools give to incoming students, faculty, and staff as a way to get to know other people on campus.

Mark Zuckerberg founded Facebook while still a student at Harvard University. Website membership was initially limited to only Harvard students, but was later expanded to include any university student, then later to high school students, and finally, to anyone aged 13 and over.

The website has more than 64 million active users worldwide. From September 2006 to September 2007, the website's ranking among all websites, in terms of traffic, increased from 60th to 7th, according to Alexa. It is also the most popular website for uploading photos, with 14 million uploaded daily. Due to the website's popularity, Facebook has met with a certain amount of criticism and controversy in its short lifespan because of privacy concerns, the politics of its founders, and censorship issues.