Facebook is a social networking website, that was launched on February 4, 2004. Facebook was founded by Mark Zuckerberg, a member of the Harvard class of 2006 and former Ardsley High School student. Users can select to join one or more participating networks, such as a high school, place of employment, or geographic region. As of late November 2007, the website has the largest number of registered users among college-focused sites, with 55 million active members (including non-collegiate members) worldwide.