Twitter

Is a free social networking and micro-blogging service that allows
users to send "updates" (text-based posts, up to 140 characters long)
via SMS, instant messaging, email, to the Twitter website, or an
application such as Twitterrific. Twitter was founded in March 2006 by
San Francisco start-up company Obvious Corp. In April 2007, Obvious, LLC spun off the service as a separate entity under the name Twitter, Inc. with Jack Dorsey as CEO.