Almost 30 years after setting up a small IT business with his childhood friend Paul Allen, Bill Gates is stepping down as the chairman of the world's biggest software company.

Mr Gates, who is now one of the world's richest men with an estimated $58 billion fortune, will today vacate his role at Microsoft to concentrate on the charitable foundation he set up with his wife, Melinda.

Although he will become a full-time philanthropist, Mr Gates will remain on Microsoft's board in a non-executive role, and as the company's largest shareholder.

A programming genius, Mr Gates’s instinctive business nous helped Microsoft grow from a small 30-man operation based in Albuquerque, New Mexico to a multi-billion dollar corporation that employs 80,000 people across 100 countries.

Mr Gate’s masterstroke came back in 1980 when IBM, the computer manufacturer, approached him to design an operating system for its PCs.

Mr Gates created the PC-DOS system for IBM for a one off-fee of $80,000 but crucially kept the copyright for the product, which formed the foundation for Microsoft.

The company grew to dominate the desktop with its Windows operating system, first launched in 1985, and which is still used on 90 per cent of the world’s computers.

Microsoft Office, launched in 1989, created the word processer and database tools used in the majority of the globe’s homes and offices.

But crucially, Microsoft’s control of the desktop could not be translated to ruling cyberspace. Mr Gates has said that the decision not to create a dedicated search engine as “stupid as hell,” with Google gaining dominance over the web.

Now, after Microsoft has failed to acquire Yahoo, the online battle is left to his new charges.

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