Twitter, Inc.
Type Private
Founded 2006
Headquarters San Francisco, California, USA
Key people Jack Dorsey, Chairman
Evan Williams, CEO
Biz Stone, Creative Director
Industry mobile social network service, micro-blogging
Employees 34
Website http://twitter.com/

Twitter is a social networking and micro-blogging service created by then Cornell student Jack Dorsey that enables its users to send and read other users' updates known as tweets. Tweets are text-based posts of up to 140 characters in length. Updates are displayed on the user's profile page and delivered to other users who have signed up to receive them. Senders can restrict delivery to those in their circle of friends . Users can send and receive updates via the Twitter website, SMS, RSS , or through applications such as Tweetie, Twitterrific, Twitterfon, TweetDeck and feedalizr. The service is free to use over the web, but using SMS may incur phone services provider fees.

Twitter has received extensive visibility and popularity worldwide. Twitter is often described as the "SMS of Internet", in that the site provides the back-end functionality to other desktop and web-based applications to send and receive short text messages, often obscuring the actual website itself.

Four gateway numbers are currently available for SMS — short codes for the United States, Canada, and India, and a United Kingdom-based number for international use. There is also a short code for Vodafone users from the UK. Several third parties offer posting and receiving updates via email.

Estimates of the number of daily users vary as the company does not release the number of active accounts. In November 2008, Jeremiah Owyang of Forrester Research estimated that Twitter had 4-5 million users. A February 2009 Compete.com blog entry ranks Twitter as the third largest social network , and puts the number of unique monthly visitors at roughly 6 million and the number of monthly visits at 55 million.In March 2009, a Nielsen.com blog ranked Twitter as the fastest growing site in the Member Communities category for February 2009. Twitter had a growth of 1382%, Zimbio had a growth of 240%, followed by Facebook with a growth 228%.

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