1955 – Born William Henry Gates III to a wealthy and influential Seattle family.
1968 – Shows an aptitude for mathematics and science as a schoolboy, and is allowed to skip maths classes to learn simple computer programming techniques before going on to Harvard to study for a pre-law degree.
1975 – Drops out of Harvard to launch new partnership with school friend Paul Allen, called Micro-soft. The duo initially start by making programs for popular home computers.
1980 – Moderately successful, Microsoft is approached by IBM to produce operating software for its new PC computers.
1985 – Microsoft launches the first version of its graphical operating system, Windows, which brings more success and by 1989 becomes the company's central product.
1986 – A stock market flotation makes Gates and Allen rich, along with several of their colleagues.
1989 – Windows is supplemented by a new series of productivity programs called Microsoft Office. (By 2007 around 90% of the world's computers were running Office.)
1993 – Microsoft's increasing success pushes Gates's wealth into the stratosphere, turning him into a billionaire. Forbes magazine names him the richest person in the world - a position he retains until 2007, when he is surpassed by Mexican telecoms magnate Carlos Slim Helu after giving away much of his fortune to charitable causes.
1997 – Microsoft's moves into the burgeoning internet market are met with resistance, as the US Justice Department files an antitrust claim against the company, accusing it of using its market dominance to force people into using its Internet Explorer browser and unfairly crushing its competitors.
1999 – With Microsoft shares rising rapidly at the height of the dotcom boom, Gates' wealth surpasses $100bn.
2000 – A ruling by a US court calls Microsoft an "abusive monopoly" and suggests that the company should be broken into two separate entities, though that decision is overturned a year later.
2006 – Still aged just 51, Gates announces that he plans to step down from activities at Microsoft in two years' time to concentrate on a new career as a full-time philanthropist.
2007 – Billionaire investor Warren Buffet pledges $1.5bn a year to the Gates Foundation, the largest philanthropic gift in history.
