Bill Gates, who never finished his degree at Harvard, was named the world's richest man in 1995. His wealth came through the founding of Microsoft, the company he started with Paul Allen in 1975. Although Microsoft is synonymous with the rise of personal computers, Bill Gates and Paul Allen did not invent personal computers; they found ways to improve existing systems.

Traf-O-Data and Altair BASIC

Gates and Allen created the Traf-O-Data traffic measurement system while they were teenagers, but it was not a commercial success. While studying at Harvard, Gates contacted MITS, the manufacturers of Altair personal computers, and offered to write software for them. The Altair had no screen or keyboard. Gates and Allen adapted Altair's BASIC language to make the machine easier to use. This language formed the basis of Microsoft's programs until the development of MS-DOS.

Microsoft and More

In 1981 Microsoft bought the "DOS" operating system, which was altered and renamed MS-DOS. This became the standard system for running personal computers. Microsoft went on to develop Windows, a graphical user interface that was more user-friendly and similar to the system used in the Apple Macintosh. Gates retired in 2007 to run the Bill and Melinda Gates Foundation with his wife. The foundation works with inventors on projects such as improved toilet facilities for impoverished countries.