Facebook began in February 2004. Mark Zuckerberg, then a student at Harvard, noticed that his school did not publish a directory of all the students and their photos like other schools did. He decided to fill this need by creating Facebook. Within a few weeks of the website’s launch, most of Harvard’s students had accounts on the social networking ’site. The website quickly grew to include members of other nearby colleges, allowing students from other campuses to connect and communicate easily. Peter Thiel, the co-creator of Paypal, was so impressed with the website that he invested $500,000 into it. By December, the website had over 1 million users. Mark Zuckerberg dropped out of Harvard and set up shop in Palo Alto, California.

Since then, Facebook has become open to everyone. It still shows its roots in young professional culture, though: over 4 million of its users are from the 25 and older crowd. It also encourages the formation of groups along intellectual and geographical lines by making it nearly impossible for users to get much use out of the website without joining a geographical, corporate, and/or school-specific network.