Jack Dorsey is another Twitter billionaire.
An integral part of Twitter from its beginning, co-founder Dorsey credits his interest in maps and how cities work for the inspiration behind the micro-messaging platform.
"When I was 15, I got really into maps and how cities work, and I taught myself how to program," the founder told CNNMoney in a previous interview. Dorsey moved to Manhattan to work for a dispatch firm before working on a project that would eventually become Twitter.
Dorsey owns 4.9% of the company, a stake worth $1 billion at the opening price.
As it transformed from startup to a full-fledged company, Dorsey's role changed. He was forced to step down as Twiiter CEO in 2008, becoming a chairman on the company's board. Dorsey launched a separate company, Square, aimed at transforming mobile payments. He later returned to Twitter, splitting time between the two companies. Dorsey has once again scaled back his day-to-day involvement at Twitter but remains an active influence, guiding the company through decisions like scooping up Instagram competitor Vine.