William Henry "Bill" Gates III, KBE (born October 28, 1955), is an American business magnate, philanthropist, the world's third richest person (as of February 8, 2008), the second richest American (as of October 10, 2008), and chairman of Microsoft, the software company he founded with Paul Allen. During his career at Microsoft, Gates held the positions of CEO and chief software architect, and remains the largest individual shareholder with more than 8 percent of the common stock. He has also authored or co-authored several books.

Gates is one of the best-known entrepreneurs of the personal computer revolution. Although he is admired by many, a large number of industry insiders criticize his business tactics, which they consider anti-competitive, an opinion which has in some cases been upheld by the courts. In the later stages of his career, Gates has pursued a number of philanthropic endeavors, donating large amounts of money to various charitable organizations and scientific research programs through the Bill & Melinda Gates Foundation, established in 2000.

Bill Gates stepped down as chief executive officer of Microsoft in January, 2000. He remained as chairman and created the position of chief software architect. In June, 2006, Gates announced that he would be transitioning from full-time work at Microsoft to part-time work at Microsoft and full-time work at the Bill & Melinda Gates Foundation. He gradually transferred his duties to Ray Ozzie, chief software architect and Craig Mundie, chief research and strategy officer. Gates's last full-time day at Microsoft was June 27, 2008. He remains at Microsoft as a part-time, non-executive chairman.

Early life

Gates was born in Seattle, Washington, to William H. Gates, Sr. and Mary Maxwell Gates. His family was upper middle class; his father was a prominent lawyer, his mother served on the board of directors for First Interstate BancSystem and the United Way, and her father, J. W. Maxwell, was a national bank president. Gates has one older sister, Kristi (Kristianne), and one younger sister, Libby. He was the fourth of his name in his family, but was known as William Gates III or "Trey" because his father had dropped his own "III" suffix. Early on in his life, Gates's parents had a law career in mind for him.

At thirteen he enrolled in the Lakeside School, an exclusive preparatory school. When he was in the eighth grade, the Mothers Club at the school used proceeds from Lakeside School's rummage sale to buy an ASR-33 teletype terminal and a block of computer time on a General Electric (GE) computer for the school's students. Gates took an interest in programming the GE system in BASIC and 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. When he reflected back on that moment, he commented on it and said, "There was just something neat about the machine." After the Mothers Club donation was exhausted, he 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 four Lakeside students—Gates, Paul Allen, Ric Weiland, and Kent Evans—for the summer after it caught them exploiting bugs in the operating system to obtain free computer time.