Doug Engelbart
Like Tim Berners-Lee, ex-radar technician Engelbart gave away a billion-dollar invention - in fact he made a habit of it. While working at Stanford University in the late 60s, he came up with the mouse, a Windows-style interface and a primitive form of HTML, none of which were taken seriously at the time. Engelbart still works in Silicon Valley, running the Bootstrap Institute, in offices rented to him by Apple - one of many companies that probably owe their fortunes to his ideas.

Vint Cerf and Bob Kahn
In a time of many networks, the internet was designed to be the one to rule them all. This was made possible by a system known as Transmission Control Protocol/Internet Protocol, which defined how data was formatted and how fast it could travel. According to legend, it was Vint Cerf who originally sketched the solution on the back of an envelope. He and Kahn worked very closely with each other throughout the net's crucial early development.

Ray Tomlinson
Tomlinson still works for BBN (co-designers of Arpanet) where in 1972 he thought up his revolutionary email programme and added the now familiar @ symbol. By the following year, email accounted for 75 per cent of all Arpanet traffic.

Mark Andreessen
Andreessen was still an undergraduate when he refined Tim Berners-Lee's original browser into a consumer application known as Mosaic. Released in 1993 it became the first popular download and led to consumers switching onto the web in their millions. Andreessen later co-founded Netscape.

Steve Bellovin
Nearly 15 years before the Web, Bellovin created Usenet, a decentralised network of newsgroups and bulletin boards that quickly outgrew its campus roots to become the first network effectively run by its users. It was also the first to be overrun by spam, although it is still used today.