Investing.com - Jack Dorsey is a busy man. He is CEO of Twitter and Square (NYSE:SQ), both of which he co-founded.Dorsey's fascination with tech began at an early age. Born in St Louis in 1976, he started creating open source software in his teens.He attended the University of Missouri before transferring to New York University, where he dropped out one semester shy of graduation in 1999.In 2000, Dorsey launched his first company, which dispatched couriers, taxis and emergency service vehicles from the Internet. It was at that time that he started developing the prototype for Twitter. Dorsey and three others launched Twitter in July 2006. Dorsey stepped down as CEO in 2010. By then, he and a partner were busy developing the technology behind Square, a mobile payments company. With Dorsey as CEO, they launched the famous square device that attaches to iPhones and similar devices in 2010. Both Twitter and Square went public in 2015, the same year Dorsey returned to Twitter as CEO. As CEO of Square, Dorsey has embraced bitcoin, calling it a "transformational technology." The company introduced bitcoin trading on its cash app in 2017 and plans on adding more bitcoin services in the future.With his stakes in Twitter and Square, Dorsey is worth an estimated $3.6 billion according to Forbes. He's considered one of the world's most eligible bachelors.