Jack Dorsey

Computer programmer and entrepreneur. Jack Dorsey is best known as the creator of Twitter. He grew up in St. Louis, Missouri. After a brief stint at the Missouri University of Science and Technology, Dorsey transferred to New York University. In the tradition of computer science entrepreneurs such as Bill Gates, Steve Jobs and Mark Zuckerberg, he dropped out of college before receiving his degree. On March 21, 2006, Jack Dorsey posted the world's first tweet: "just setting up my twttr." Dorsey was named the company's chief executive officer. He removed his nose ring in an attempt to look the part of a mature Silicon Valley executive, though he kept his boyish, mop-like haircut and abstract, forearm-length tattoo whose shape represented, among other things, the human clavicle bone. Co-founder Evan Williams replaced Dorsey as Twitter's CEO in October 2008, with Dorsey staying on as company chairman.