In 1991 a young student, Linus Tovalds, bought a PC and began writing a new software program. It started as a hobby, but in a few years he and a global alliance of hackers, linked by the net, had developed an operating system that now threatens Microsoft. GNU/Linux is used by millions, and most troubling of all for the corporate giants, it is free. In this definitive account, the author tells the astonishing David-and Goliath story of Linux, placing it in the broader history of the free software movement, and shows what can be achieved when creativity and co-operation rise above the profit motive.