Jack Dorsey is an American technology entrepreneur who co-founded Twitter and Square. He was born in 1976 in Missouri and became interested in computers at a young age. In 2006, he co-founded Twitter, the social media platform where users post messages. He later founded Square, a financial services and digital payments company, in 2009. As of 2015, Dorsey's net worth was estimated to be $2.4 billion due to his success with Twitter and Square.