Total Users : 600 Million
Indian Users: 18.8 Million

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.
Facebook was founded by Mark Zuckerberg with his college roommates and fellow computer science students Eduardo Saverin, Dustin Moskovitz and Chris Hughes. The website's membership was initially limited by the founders to Harvard students, but was expanded to other colleges in the Boston area, the Ivy League, and Stanford University. It gradually added support for students at various other universities before opening to high school students, and, finally, to anyone aged 13 and over, but based on Consumers Reports.org on May 2011, there are 7.5 million children under 13 with accounts, violating the site's terms.Users can create profiles with photos, lists of personal interests, contact information, and other personal information. Users can communicate with friends and other users through private or public messages and a chat feature. They can also create and join interest groups and "like pages", some of which are maintained by organizations as a means of advertising.
To allay concerns about privacy, Facebook enables users to choose their own privacy settings and choose who can see specific parts of their profile. The website is free to users, and generates revenue from advertising, such as banner ads. Facebook requires a user's name and profile picture to be accessible by everyone. Users can control who sees other information they have shared, as well as who can find them in searches, through their privacy settings.