Jack Dorsey is Twitter’s co founder. In 2010, Twitter had more than 105 million users who “tweet” about 55 million times a day.

Until fourteen years old, Jack Dorsey, grew up in Saint Louis, Missouri. He had studied science and Technology at University of Missouri and then joined University of New York.

In 2000, he founded a service which allows to send messages from the Web in order to find quickly a taxi. The idea of communicating in a real time comes from AOL instant messenger.

He meets Odeo’s founders, Noah Glass and Evan Williams. Noah Glass markets AudioBlogger, an application allowing to publish audio files on a blog via telephone. Evan Williams is known as co-founder of Pyra Labs, which in origin was a platform of blogs, taken over by Google in 2003.

Together they create a Twitter’s prototype. The idea is allowing users to say what they are doing via SMS. Open to public on July 13 2006, the first version is called stat.us and then twitter.

Until October 16 2008, Jack Dorsey is a CEO. Then he became chairman of the board, and Evan Williams succeeded him.

With its ease of use, Twitter becomes rapidly very popular. In 2007, Twitter won South by Southwest Web awards for blogs.

In May 2009, Dorsey announced his new project, Square, originally the name was Squirrel. This is a start-up which allows people to receive payments by credit card through a small device installed on their mobile phone.