Williams Gate 3, Worlds richest billionaire.

Age: 51

Fortune: self made

Source: Microsoft

Net Worth: $56.0 bil

Country Of Citizenship: United States

Residence: Medina, Washington , United States, North America

Industry: Software

Marital Status: married, 3 children

Education: Harvard University, Drop Out

After numerous delays, Microsoft visionary released latest operating system, Vista, in January. Last June announced his retirement from company he cofounded 31 years ago. The Harvard dropout who promised "a computer on every desk and in every home" now focusing time and talents on tackling diseases (hepatitis B, AIDS, malaria) in Africa, boosting America's lackluster high school graduation rate and helping women abroad start small businesses.

This summer bridge buddy Warren Buffett pledged majority of his Berkshire Hathaway stock to Bill & Melinda Gates Foundation over the next 20 years, potentially doubling foundation's endowment. Sells 20 million Microsoft shares a quarter, plows proceeds into personal investment vehicle Cascade.

Today more than half of net worth invested outside Microsoft.
Distribution of Billionaires by ResidenceDiameter of disc reflects size of fortune. The red disc indicates William Gates III .