William Henry Gates III (born October 28, 1955) is an American businessman and philanthropist. A pioneer of the microcomputer revolution of the 1970s and 1980s, he co-founded the software company Microsoft in 1975 with his childhood friend Paul Allen. Following Microsoft's initial public offering in 1986 and the subsequent increase in its stock price, Gates became the world's then-youngest billionaire in 1987, at age 31. Forbes magazine ranked him as the world's wealthiest person in their The World's Billionaires list for 18 out of 24 years between 1995 and 2017, including 13 years consecutively from 1995 to 2007. Gates became the first centibillionaire in 1999, when his net worth briefly surpassed US$100 billion. According to Forbes, as of July 2026, his net worth stood at US$106.5 billion, making him the 19th-wealthiest individual in the world.
Gates is also known for his extensive philanthropic work, particularly through the Gates Foundation, the world's largest private charitable organization, which he co-chaired with his then-wife Melinda French Gates from 2000 until 2024. He has focused on global health, education, and poverty alleviation, and has funded efforts to combat diseases such as tuberculosis, malaria, and polio. In 2010, he and Warren Buffett founded the Giving Pledge, encouraging billionaires to donate at least half their wealth to philanthropy. Gates has received numerous honors, including the Presidential Medal of Freedom in 2016.
Early life and education
William Henry Gates III was born on October 28, 1955, in Seattle, Washington, as the only son of Bill Gates Sr. (1925–2020) and his first wife, Mary Maxwell Gates (1929–1994). His ancestry includes English, German, and Irish/Scots-Irish. His father was a prominent lawyer, and his mother served on the board of directors of First Interstate BancSystem and United Way of America. Gates's maternal grandfather, J. W. Maxwell, was a national bank president. Gates has an older sister, Kristi, and a younger sister, Libby. He is the fourth of his name in his family, but is known as William Gates III or "Trey" because his father had the "II" suffix. The family lived in the Sand Point area of Seattle in a home that was damaged by a rare tornado when Gates was 7.
When Gates was young, his parents wanted him to pursue a career in law. During his childhood, his family regularly attended a church of the Congregational Christian Churches, a Protestant Reformed denomination. Gates was small for his age and was bullied as a child. The family encouraged competition; one visitor reported that "it didn't matter whether it was hearts or pickleball or swimming to the dock; there was always a reward for winning, and there was always a penalty for losing."
At age 13, Gates enrolled in the private Lakeside Prep School. When he was in the eighth grade, the Mothers' Club at the school used proceeds from a rummage sale to buy a Teletype Model 33 ASR terminal and a block of computer time on a General Electric (GE) computer for the students. Gates took an interest in programming the GE system in BASIC, and he was excused from math classes to pursue his interest. He wrote his first computer program on this machine, an implementation of tic-tac-toe that allowed users to play games against the computer. Gates was fascinated by the machine and how it would always execute software code perfectly.
After the Mothers Club donation was exhausted, Gates and other students sought time on systems, including DEC PDP minicomputers. One of these systems was a PDP-10 belonging to Computer Center Corporation (CCC), which banned Gates, Paul Allen, Ric Weiland, and Gates's best friend and first business partner, Kent Evans, for the summer after it caught them exploiting bugs in the operating system to obtain free computer time. The four students formed the Lakeside Programmers Club to make money. At the end of the ban, they offered to find bugs in CCC's software in exchange for extra computer time. Rather than using the system remotely via Teletype, Gates went to CCC's offices and studied source code for various programs that ran on the system, including Fortran, Lisp, and machine language. The arrangement with CCC continued until 1970, when the company went out of business.
In 1971, a Lakeside teacher enlisted Gates and Evans to automate the school's class-scheduling system, providing them computer time and royalties in return. The duo worked diligently to have the program ready for their senior year. Towards the end of their junior year, Evans was killed in a mountain climbing accident, which Gates described as one of the saddest days of his life. He then turned to Allen, who helped him finish the system for Lakeside.
At age 17, Gates formed a venture with Allen called Traf-O-Data to make traffic counters based on the Intel 8008 processor. In 1972, he served as a congressional page in the House of Representatives. He was a national merit scholar when he graduated from Lakeside School in 1973. He scored 1590 out of 1600 on the SAT and enrolled at Harvard University in the autumn of 1973.
Gates did not stay at Harvard long enough to choose a concentration, but took mathematics (including Math 55) and graduate-level computer science courses. While at Harvard, he met fellow student and future Microsoft CEO Steve Ballmer. Gates left Harvard after two years while Ballmer stayed and graduated magna cum laude. Years later, Ballmer succeeded Gates as CEO.
Founding Microsoft
In 1975, Gates and Allen co-founded Microsoft in Albuquerque, New Mexico, after seeing an article about the Altair 8800 microcomputer. They developed a BASIC interpreter for the Altair, which became the company's first product. Gates took a leave of absence from Harvard to work on the project, and he never returned to complete his degree. Microsoft's early success came from licensing its software to various computer manufacturers, including IBM, which led to the development of MS-DOS in 1981. The operating system became the foundation for Microsoft's dominance in the personal computer market.
Gates served as Microsoft's CEO for 25 years, from its incorporation in 1981 until 2000. He also held the roles of president and chairman of the board. Under his leadership, Microsoft launched Windows in 1985, which became the most widely used operating system in the world. The company's initial public offering in 1986 made Gates a multimillionaire, and by 1987, at age 31, he became the world's youngest billionaire at the time.
Leadership and innovation
Gates was known for his intense focus on product development and his competitive business strategies. He oversaw the creation of key products such as Microsoft Office, Internet Explorer, and the Xbox gaming console. In 2000, he stepped down as CEO, succeeded by Steve Ballmer, and transitioned to the role of chief software architect, a position he held until 2008. During this period, he continued to influence Microsoft's technical direction, including the development of the .NET framework and the company's foray into cloud computing.
In 2014, Gates stepped down as chairman of the board and became technology adviser to CEO Satya Nadella and other Microsoft leaders, a position he still holds. He resigned from the board in 2020. His ongoing involvement has included advising on artificial intelligence initiatives, as Microsoft has invested heavily in OpenAI and integrated Generative AI capabilities into its products.
Philanthropy and the Gates Foundation
Gates has increasingly focused on philanthropy since the late 1990s. In 2000, he and his then-wife Melinda French Gates established the Bill & Melinda Gates Foundation, which became the world's largest private charitable organization. The foundation focuses on improving global health, reducing poverty, and expanding educational opportunities. Gates has been particularly active in funding research and vaccination programs for infectious diseases, including tuberculosis, malaria, and polio. The foundation has also supported agricultural development and financial services for the poor in developing countries.
In 2010, Gates and Warren Buffett founded the Giving Pledge, an initiative that encourages billionaires to commit at least half of their wealth to philanthropic causes. Gates has also invested in clean energy technologies through Breakthrough Energy, a company he founded to address climate change. After Melinda French Gates resigned as co-chair in 2024 following their divorce, the foundation was renamed the Gates Foundation, with Gates as its sole chair.
Other ventures and investments
Beyond Microsoft and the foundation, Gates has founded and chaired several other companies, including BEN, Cascade Investment, TerraPower, Gates Ventures, and Breakthrough Energy. TerraPower focuses on advanced nuclear reactor designs, while Breakthrough Energy supports clean energy innovation. Gates has also made personal investments in various sectors, including agriculture and technology. He has shown a keen interest in Artificial intelligence, investing in companies like OpenAI and supporting research in Machine learning and Deep learning.
Gates has also been an active investor in AI-related startups and has spoken publicly about the potential of Large language models and Transformer (architecture) architectures to transform industries. He has collaborated with organizations like MIT CSAIL and Stanford AI Lab on AI research and policy discussions.
Recognition and legacy
Gates has received numerous honors and accolades throughout his career. In 1999, Time magazine named him one of the 100 most influential people of the 20th century. In 2016, he and Melinda French Gates were awarded the Presidential Medal of Freedom for their philanthropic work. Gates has also been the subject of several documentary films, including "Inside Bill's Brain: Decoding Bill Gates" (2019). In 2025, he published the first of three planned memoirs, "Source Code: My Beginnings," which details his early life and the founding of Microsoft.
Gates's legacy is multifaceted, encompassing his role as a technology pioneer, his business acumen, and his philanthropic impact. He has been both praised for his contributions to computing and criticized for Microsoft's business practices, particularly in the 1990s antitrust case. Nevertheless, his influence on the software industry and global health is undeniable, and he continues to shape discussions on technology and social issues.
Personal life
Gates married Melinda French in 1994, and they had three children together. The couple divorced in 2021, but continued to co-chair the foundation until 2024. Gates is known for his love of reading and his interest in a wide range of topics, from history to science. He maintains a blog, GatesNotes, where he shares his thoughts on books, technology, and global issues. In recent years, he has become a vocal advocate for pandemic preparedness and has funded research on vaccine distribution and disease surveillance.