Bill Gates earned his fortune by founding Microsoft together with Paul Allen in 1975. They started by developing software for the first personal computers. The most important step was the contract with IBM in 1980, when Microsoft provided the MS-DOS operating system. This success established the company as a leader in the industry. Later, Windows became the dominant OS in the world. Gates retained a significant share of Microsoft stocks, which brought him billions. He also invested in other companies and created a charitable foundation with his wife.
