Facebook is a social networking service and website launched in February 2004, operated and privately owned by Facebook, Inc. As of July 2011, Facebook has more than 750 million active users. Users may create a personal profile, add other users as friends, and exchange messages, including automatic notifications when they update their profile. Facebook users must register before using the site. Additionally, users may join common-interest user groups, organized by workplace, school or college, or other characteristics. The name of the service stems from the colloquial name for the book given to students at the start of the academic year by university administrations in the United States to help students get to know each other better. Facebook allows any users who declare themselves to be at least 13 years old to become registered users of the website.
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