29 October 1955: Bill Gates born in Seattle to William H. Gates II and Mary Gates.

1973: Gates enters Harvard and lives down the hall from current Microsoft CEO Steve Ballmer.

1 February 1975: After being inspired by an article in popular electronics, Gates teams up with Paul Allen to produce a BASIC interpreter for the MITS Altair 8800 computer. The pair licence the software to MITS. Gates later leaves Harvard to pursue Microsoft full time.

29 November 1975: First reference to 'Micro-soft' by Bill Gates in a letter to Paul Allen to describe their partnership.

3 February 1976: Gates raises the issue of software piracy in 'An Open Letter to Hobbyists' urging them not to copy software unlawfully.

26 November 1976: Microsoft registered as a trade name.

13 December 1977: Gates arrested for racing his Porsche 911 in the New Mexico desert.

25 June 1981: Microsoft incorporated, Gates becomes president and chairman of the board.

8 December 1981: IBM PC introduced using Microsoft's MS-DOS software. Gates licensed the software from Seattle Computer Products.

20 November 1985: First version of Microsoft Windows ships.

12 November 1990: Gates speaks at Comdex tradeshow to unveil his vision of the future of computing in his 'Information at Your Fingertips' keynote.

23 June 1992: Gates awarded National Medal of Technology for Technological Achievement by President George Bush to recognise "his contribution to the development of the personal computing industry".

1 January 1994: Gates marries Melinda French.

24 November 1995: Gates book, The Road Ahead, released. Over 1.5 million copies in 20 languages produced on first print run.

21 July 1998: Steve Ballmer takes on role as Microsoft president. Gates continues as chairman and CEO.

January 2000: Bill and Melinda Gates Foundation formed through the merger of the Gates Learning Foundation and William H. Gates Foundation. It aims to help reduce inequities in the US and around the world.

13 January 2000: Gates gives up CEO title to Ballmer to become chairman and chief software architect.

15 June 2006: Gates announces plans to transition from his day-to-day role at Microsoft by 31 July 2008, allowing him to devote more time to the Bill and Melinda Gates Foundation.