Facebook gradually added support for students at various other universities, and eventually to high school students.
Since 2006, anyone who claims to be at least 13 years old has been allowed to become a registered user of Facebook, though variations exist in this requirement, depending on local laws.
After registering, users can create a customized profile indicating their name, occupation, schools attended and so on.
Users can add other users as "friends", exchange messages, post status updates, share photos, videos and links, use various software applications ("apps"), and receive notifications of other users' activity.
The founders initially limited the website's membership to Harvard students.