Zuckerberg wrote a program called "Facemash" in 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 has more than 2.2 billion monthly active users as of January 2018.

Its popularity has led to prominent media coverage for the company, including significant scrutiny over privacy and the psychological effects it has on users.

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.

Additionally, users may join common-interest user groups organized by workplace, school, hobbies or other topics, and categorize their friends into lists such as "People From Work" or "Close Friends".

Additionally, users can report or block unpleasant people.

The Facemash site was quickly forwarded to several campus group list-servers, but was shut down a few days later by the Harvard administration.

Zuckerberg faced expulsion and was charged by the administration with breach of security, violating copyrights, and violating individual privacy. Zuckerberg expanded on this initial project that semester by creating a social study tool ahead of an art history final exam.

the benefits are many." Six days after the site launched, Harvard seniors Cameron Winklevoss, Tyler Winklevoss, and Divya Narendra accused Zuckerberg of intentionally misleading them into believing that he would help them build a social network called Harvard

They claimed that he was instead using their ideas to build a competing product.

The name comes from the face book directories often given to American university students.