Famously known as one of the cofounders of Microsoft Corp., Paul Allen became friends with Bill Gates at Lakeside School, a private school in Seattle, even though Gates was almost three years younger. But the two shared a common interest in computers and used Lakeside’s Teletype terminal to develop their programming skills.

After graduation, Allen attended Washington State University but dropped out after two years to work as a programmer for Honeywell in Boston. He later convinced Gates to leave Harvard University to establish Microsoft. Allen was inspired by the publication of a two-part article in Popular Electronics in January and February 1975 about how to build a personal computer called the MITS Altair 8800.

Allen cofounded Microsoft with Gates in Albuquerque, N.M., in 1975 and developed a Basic programming language interpreter for the Altair 8800. Allen came up with the original name of Micro-Soft, but changed it in 1976 to Microsoft. In 1980, Microsoft made a deal with IBM to develop a Disk Operating System (DOS) for the soon to be announced IBM PC.

Instead of developing DOS, Allen was instrumental in purchasing an operating system written by Tim Paterson, who was employed at Seattle Computer Products at the time. As a result of this transaction, Microsoft was able to secure a contract to supply the DOS that would eventually run on IBM’s PC line of computers. This contract with IBM was the watershed moment in Microsoft history.

After a serious bout with Hodgkin’s lymphoma in 1982 and a successful recovery through radiation therapy, Allen began scaling back his involvement with Microsoft and turned to other pursuits. He used his enormous wealth first and foremost for philanthropic purposes, establishing the Paul G. Allen Family Foundation 1986, which awards approximately $30 million in grants annually. He has also contributed generously to his alma mater, Washington State University, including a $14 million donation to the Paul G. Allen Center for Computer Science & Engineering.

His philanthropic efforts notwithstanding, Allen has also been involved in other pursuits such as the first privately funded spacecraft, SpaceShipOne, and the development of the online Allen Brain Atlas. He has a penchant for sports as well, purchasing the Portland Trailblazers basketball franchise in 1988 and the Seattle Seahawks football franchise in 1997, and becoming part owner of the Seattle Sounders FC, a Major League Soccer franchise in 2009.