Facebook was launched in 2004 by Mark Zuckerberg and other Harvard University students initially only for Harvard students. It later expanded to everyone with a valid email address age 13 and older. Facebook has grown rapidly since its launch, reaching over 1 billion active users by 2012. It started as a social networking platform for photos and profiles but has since added many new features like events, pages, messenger, live streaming and more to evolve with its growing user base.