Microsoft was founded in 1975 and put a computer in the average home, which had not previously seemed like a sensible ambition. Bill Gates co-founded it, ran it as it became dominant, and spent years as the richest person alive.

Dominance drew fire. A landmark antitrust case tested how far a software monopoly could go, and the answer reshaped the industry. In the 2000s he stepped back from running the company to do something else with the money.

The second act was the harder one: applying a builder's rigour to problems that resist quick wins.

The Bill & Melinda Gates Foundation put vast sums into global health, disease eradication and education, and more recently into climate and clean energy. The approach is recognisably an engineer's: measure everything, fund what the data supports, keep going after problems that resist quick wins.

He also co-founded the Giving Pledge, which asks the very wealthy to commit most of their fortunes to philanthropy — and made that a public commitment rather than a private one. The second act changed what a technology fortune is understood to be for.

Gates grew up in Seattle and learned to program at Lakeside School, where he met Paul Allen. He left Harvard in 1975 to start Microsoft with Allen in Albuquerque. The breakthrough came in 1980, when IBM needed an operating system for its personal computer. Microsoft supplied MS-DOS but kept the right to license it to other manufacturers, the decision that made the company.

Windows, Office and a 1986 stock-market listing turned that position into a fortune. In 1998 the US Department of Justice sued Microsoft over bundling its Internet Explorer browser with Windows. A judge ordered the company broken up in 2000, but the order was overturned on appeal and the case ended in a 2001 settlement. Gates handed the chief executive role to Steve Ballmer in 2000 and stopped working full-time at Microsoft in 2008.

The foundation took the name Gates Foundation after he and Melinda French Gates divorced in 2021 and she left in 2024. In May 2025 Gates said he would give away nearly all of his remaining wealth through the foundation over the next twenty years, and that it would close at the end of 2045. He also founded Breakthrough Energy in 2015 to back clean-energy technology.