William Henry Gates III

Gates and Paul Allen telephoned MITS, the maker of the Altair 8800, and told the company they had a working BASIC interpreter for the machine. They had not written a line of it; Gates then built the program in about eight weeks on Harvard's PDP-10, under the deadline the sale had created.¹ The company the two founded to sell it, Microsoft, built and sold the operating systems and applications software, including MS-DOS, Windows, and Office, that became the standard layer for personal computers and created the modern commercial software industry. Since stepping back from Microsoft he has run the Bill & Melinda Gates Foundation, the world's largest private philanthropic foundation, and is now its sole chair.

Background

William Henry Gates III, nicknamed "Trey," was born in Seattle, Washington, on October 28, 1955, into a comfortable, high-achieving professional family. His father was a prominent Seattle lawyer who co-founded the firm Preston, Gates & Ellis in 1964; his mother served on the boards of United Way and First Interstate BancSystem, and his maternal grandfather was a national bank president. The household barred television on school nights, and Gates has said he decided at age seven to read the encyclopedia cover to cover.²

He attended Lakeside School, a private Seattle prep school, where the Mothers' Club used rummage-sale proceeds to buy a Teletype terminal with paid access to a General Electric time-sharing computer at forty dollars an hour.¹ Gates wrote his first program, a tic-tac-toe game, at thirteen, mentored by teacher Bill Dougall, and met Paul Allen at Lakeside in 1968, forming a close working partnership.¹ A closer friend, Kent Evans, with whom Gates planned to build things, died in a mountain-climbing accident at seventeen; Gates has said he resolved to do the things he and Kent had talked about, but without Kent.² As teenagers Gates and Allen built Traf-O-Data, a traffic-counting product that earned roughly twenty thousand dollars, and Gates took a paid job debugging power-grid software for TRW. He entered Harvard in 1973, solved an open pancake-sorting problem, met Steve Ballmer in his dorm, and left without a degree; Harvard awarded him an honorary one in 2007.

Getting started

In December 1974, Allen saw the Popular Electronics cover story on the Altair 8800, an early microcomputer, and told Gates, "This thing is happening without us."¹ The two telephoned MITS, the machine's maker, and claimed to have a working BASIC interpreter for it, though they had built nothing; MITS agreed to a demonstration. Gates then wrote the interpreter in about eight weeks on Harvard's PDP-10, with floating-point routines contributed by Monte Davidoff, who was paid four hundred dollars.¹ Allen flew to Albuquerque in March 1975 and loaded the code onto a real Altair for the first time; it ran correctly on the first attempt. Gates and Allen founded Microsoft in Albuquerque on April 4, 1975, with first-year revenue of 16,005 dollars. Gates negotiated the equity split from fifty-fifty toward himself, first to sixty-forty and later sixty-four to thirty-six. In February 1976 he wrote an "Open Letter to Hobbyists," arguing that software developers deserved payment amid widespread unauthorized copying.

What he built

Microsoft relocated to Seattle and, in 1980 and 1981, landed the deal to supply MS-DOS for IBM's original personal computer, which became the industry standard and the basis of Microsoft's dominance. Microsoft went public on March 13, 1986; Gates, then thirty, retained roughly a forty-five percent stake worth about 350 million dollars at the offering and became a billionaire in 1987, then the world's youngest. Windows and Office grew into the dominant PC platform and productivity suite worldwide for decades. By 1995 his fortune reached about 12.9 billion dollars, making him the world's richest person, and in 1999 he became the first to cross 100 billion dollars in personal wealth. He stepped down as chief executive in 2000, succeeded by Steve Ballmer, remaining chairman and chief software architect; he left day-to-day work in 2008, stepped down as chairman in 2014, and resigned from the board in 2020. In 2000 he and his then-wife Melinda French Gates co-founded the Gates Foundation, to which he has donated more than 59 billion dollars.

How he operates

Gates has described the intensity of his twenties bluntly, saying he was "monomaniacal" in a way that intimidated competitors and that he did not believe in vacations.³ He has framed his founding insight as creating rather than entering a market: when Allen showed him the magazine, there was no software industry, and the two saw they could create one.³ The Altair episode illustrates a recurring pattern, committing publicly to a deliverable before it exists, then building under the pressure the commitment creates. That analytical, technical deep-dive style carried into his data-driven approach to global health philanthropy.²

Where things stand

Gates divorced Melinda French Gates in 2021; she left the foundation's board in 2024, leaving him sole chair. As of February 2026 Forbes estimated his net worth at about 107.7 billion dollars, though much of that includes Gates Foundation Trust assets not personally accessible. The foundation approved a record 9 billion dollar payout budget for 2026 and plans to spend down and cease operating by 2045. Gates holds no formal position at Microsoft; his focus is the foundation and related vehicles such as Breakthrough Energy.

Key facts

• Microsoft's founding product, a BASIC interpreter for the Altair 8800, was sold before it had been written; Gates built it in about eight weeks to make the claim true.
• His access to a computer at Lakeside existed only because the Mothers' Club funded it with rummage-sale money.
• In 1999 Gates became the first person to reach a personal net worth over 100 billion dollars, and held the title of world's richest for the better part of two decades.
• The Gates Foundation has given away more than 59 billion dollars and plans to spend down and close by 2045.
• His childhood best friend Kent Evans died at seventeen before Microsoft was founded; Gates has said he built the company to fulfill plans they had made together.