Twitter is a social networking and microblogging website that allows registered users to send and receive short text messages called tweets. Tweets can be publicly visible or restricted to the intended audiences. Users may subscribe to other users' tweets using a process called following. Subscribers to other users' tweets are called followers.

Since its debut in July 2006, Twitter has gained worldwide popularity with some 200 million users to date. It generates some 70 million tweets a day earning it the nickname as SMS of the Internet.

Twitter was subpoenaed by a U.S. Justice on January 14, 2011 to hand over account details of WikiLeaks' founder and supporters.