The founders had initially limited the website's membership to Harvard students; however, later they expanded it to higher education institutions in the Boston area, the Ivy League schools, and Stanford University.
Facebook gradually added support for students at various other universities, and eventually to high school students as well.
Zuckerberg wrote a program called "Facemash" on October 28, 2003 while attending Harvard University as a sophomore (second year student).
According to The Harvard Crimson, the site was comparable to Hot or Not and used "photos compiled from the online facebooks of nine houses, placing two next to each other at a time and asking users to choose the 'hotter' person".
Facebook makes most of its revenue from advertisements which appear onscreen. held its initial public offering (IPO) in February 2012, and began selling stock to the public three months later, reaching an original peak market capitalization of 4 billion.
On July 13, 2015, Facebook became the fastest company in the Standard & Poor's 500 Index to reach a market cap of 0 billion.
After registering to use the site, users can create a user profile indicating their name, occupation, schools attended and so on.
Users can add other users as "friends", exchange messages, post status updates and digital photos, share digital videos and links, use various software applications ("apps"), and receive notifications when others update their profiles or make posts.