Facebook

What is facebook?
 * "Facebook** is a social networking service and website launched in February 2004 that is operated and privately owned by Facebook, Inc. As of January 2011, Facebook has more than 600 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. 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 US with the intention of helping students to get to know each other better. Facebook allows anyone who declares themselves to be at least 13 years old to become a registered user of the website."

An exerpt from a wikipedia article WITHOUT ANY AUTHOR.