Co-founder of Microsoft along with his schoolfriend Bill Gates.

Allen and Gates aspired to bring computing power to the masses and to this end in 1975 founded Microsoft. As head of research and new product development at the fledgling software company, Allen helped to engineer the MS-DOS operating system and other innovations.

In 1983 Allen developed Hodgkin's disease, a treatable but potentially fatal cancer, and decided to leave Microsoft. He went on to found Asymetrix, a company that made application development tools, in 1985.

In 1986 Allen founded his present company, Vulcan Inc., an investment vehicle. In his role as chairman, he has invested billions of dollars in companies that play a role in what he has long called the 'Wired World'. Vulcan Inc. own, or have invested in, more than 140 new media, entertainment and technology companies including cable operators, high-speed Internet access providers, entertainment companies, and e-commerce and technology firms.

A multi-billionaire, Allen has been named one of the top 15 philanthropists in America. He has created six charitable foundations and is involved in a wide range of civic activities.