Twitter is an online social networking and microblogging service that allows its users to send and read text-based messages of up to 140 characters, known as tweets. Twitter was founded in March 2006 by Jack Dorsey, and its social networking site was launched in July. Since its launch, Twitter has become one of the ten most visited sites on the Internet, and is dubbed the "Internet short message." On Twitter, unregistered users can only read tweets, while registered users can write Twitter via the website interface, short messages (SMS), or through various apps for mobile devices.
Twitter is growing rapidly. There were 400,000 chirps posted per quarter in 2007. This number increased to 100 million chirp per quarter in 2008. In February 2010, Twitter users sent 50 million chirp a day. As of March 2010, the company noted there were over 70,000 registered Twitter apps. As of June 2010, according to Twitter, around 65 million Twitter was posted every day, or about 750 chirps per second, and in March 2011, the number of Twitters posted each day reached 140 million. According to a Compete.com report, Twitter's position rose to third place as the most visited social networking site in January 2009, from which it was previously ranked twenty-two.