Facebook is a social networking service headquartered in Menlo Park, California, United States which was launched in February 2004. Until September 2012, Facebook has more than one billion active users, more than half of them use cellphones. Facebook was founded by Mark Zuckerberg with his roommates and fellow Harvard University students, Eduardo Saverin, Andrew McCollum, Dustin Moskovitz, and Chris Hughes. Membership of this website was initially limited to Harvard students only, then expanded to other colleges in Boston, Ivy League, and Stanford University.
Quora is a question-and-answer website, where people can ask questions, give answers and can also change it. It has been published by Quora Inc., whose headquarters is located in Mountain View, California.
Twitter is owned and operated by Twitter, Inc., based in San Francisco, with additional offices and servers in New York City, Boston and San Antonio. As of May 2015, Twitter has more than 500 million users, 302 million of which are active users. The high popularity of Twitter has caused this service to be used for various purposes in various aspects, for example as a means of protest, political campaigns, learning facilities, and as an emergency communication media.
Renren is a Chinese social networking website. In August 2009, Xiaonei Network officially changed its name to Renren with as domain name www.renren.com.
Plurk is a free social networking and microblog service that allows users to send updates (known as a plurk) through a web interface, short message, or other means, with a maximum length of 140 characters. This update will be displayed on the user's web page using a timeline that displays all received updates in chronological order, and then is delivered to other incoming users. Users can respond to updates from other users of their timeline through the Plurk.com website, sender of instant messages, or short messages.
Douban is a Chinese social networking website. The website was established on March 6, 2005 by Yang Bo. The website starts with a book and audio, and provides information about books, movies, music, and other works.
LiveJournal is a virtual community where Internet users can maintain a blog, a newspaper or a diary. Each user has a profile with which to interact with communities and other users. The standard service is free but there is also the possibility to upgrade to premium account.
Odnoklassniki is a Russian social networking website owned by Mail.Ru Group. The website currently has more than 200 million registered users and 45 million daily unique visitors.