Gates began to show an early interest in software and began programming computers at the age of thirteen.
Gates wrote the school's computer program to schedule students in classes. While still a Harvard undergraduate, Bill Gates wrote a version of the programming language BASIC for the MITS Altair microcomputer.
In November 1975 Gates took a leave of absence from Harvard to work with Allen at MITS in Albuquerque. Having written the first computer language for a personal computer, Gates and Allen established the Microsoft Corporation in 1975.
In 1980 Microsoft began its domination of the fledgling microcomputer industry when Gates licensed the operating system MS-DOS to IBM for use in IBM's first personal computer.
On November 10, 1983, Microsoft Corporation formally announced Microsoft Windows, a next-generation operating system. It was just a publicity stunt. The truth was that Microsoft was nowhere near developing such a system. In this year Paul Allen left the company for health reasons. Windows 1.0 was finally released in November 1985. That same year Microsoft reported $140 million in revenue, including $46.6 million from overseas users.
In 1986, Bill Gates took Microsoft public with an initial public offering (IPO) of $21 per share. Gates held 45 % of the company's 24.7 million shares and became an instant millionaire at age 31.
Beginning in 1995, he refocused Microsoft on the development of software solutions for the Internet, in particular Microsoft's Internet Explorer Web browser and he also moved the company into the computer hardware and gaming markets with the Xbox video machine.
Gates's role at Microsoft for most of its history was primarily a company's product strategy, management and executive role. However, he was an active software developer in the early years.
He, along with others, wrote the MS-DOS operating system, the Windows operating interface, the Internet Explorer browser, and a multitude of other popular computer products.
In March 2010, Gates with net worth $53 billion, was the second wealthiest person behind Carlos Slim, but regained the top position in 2013.
On 17 October, 2017 his Net worth - US $89 billion.
It was at Lakeside School where Bill met Paul Allen , who was two years his senior. The two became fast friends, bonding on their common enthusiasm over computers, even though they were very different.
In 1970, at the age of 15, Bill Gates went into business with Paul Allen. At age 17, Gates formed a venture with Allen, called Traf-O-Data, a computer program that monitored traffic patterns in Seattle. In early 1973, Bill Gates served as a congressional page in the U.S. House of Representatives.
Gates was only 23, when he placed himself as the head of Microsoft, which grossed $2.5 million in 1978.
In middle 1981 Gates and Allen incorporated Microsoft, and Gates was appointed president and chairman of the board. Allen was named executive vice-president. Iin 1989 he founded Corbis, a digital imaging company.
In 2004, he became a director of Berkshire Hathaway, the investment company.
Bill Gates stepped down from the day-to-day operations of Microsoft in 2000, turning over the job of CEO to college friend Steve Ballmer. Gates' last full-time day at Microsoft was June 27, 2008.
His Titles are: Technology Advisor of Microsoft, CEO of Cascade Investment, Chairman of Corbis, Chairman of the TerraPower.
He also is Co-Chairman of the Bill & Melinda Gates Foundation. Now he devoted more time to charity work at the Bill and Melinda Gates Foundation.
In 1989, Bill Gates 37 he met a 28-year-old Microsoft executive named Melinda French. In time, their relationship grew as they discovered an intimate and intellectual connection. On January 1, 1994, Melinda and Bill were married in Hawaii. The couple have three children: daughters Jennifer Katharine (b. 1996) and Phoebe Adele (b. 2002) and son Rory John (b. 1999).
With the influence of his wife Melinda, Gates took an interest in filling his mother's role as a civic leader.
In 1994 he founded the William H. Gates Foundation (focusing on health issues in developing countries) and in 1997 established the Gates Library Foundation, later renamed the Gates Learning Foundation. In 2000, the couple combined several family foundations to form the Bill and Melinda Gates Foundation. They started out by making a $28 billion contribution to set up the foundation.
On June 2010 Bill and Melinda Gates and Warren Buffett started the Giving Pledge campaign. They are asking hundreds of rich Americans to pledge at least at least half their net worth to charity. At present there are 403 billionaires living in the US, according to Forbes.