Top 10 technology visionaries

2. Marc Andreessen
Shaun Nichols: In planning this list, Iain and I were stumped as to how to fill this spot. We knew that it had to be the development of the web, but we couldn't decide on giving the spot to Andreessen or Sir Tim Berners-Lee. Then Iain noted something that ultimately settled the matter.

Back when Andreessen was first developing the browser, Berners-Lee thought that it was a horrible idea. He even told Andreessen that putting images alongside text wasn't the point; that the internet should be text only.

Of course, that didn't happen. Andreessen's idea caught on and, in the years that followed, the internet blossomed from a university research tool into a vital part of world culture.

Iain Thomson: This was an argument that went on for a good half a pint. The father of the web versus the person who opened it up. It's a bit like comparing Enzo Ferrari to Henry T. Ford.

Berners-Lee worked out a way to link huge number of people via simple networking protocols so that they could speak to each other via text and documents in a way that surmounted the ARPANET system. But it was Andreessen who took it to the masses.

The Netscape browser was to the internet what the GUI was to the command line interface, or Grace Hopper to programming. It made computing more mainstream and accessible to someone who, amazingly enough, might not be willing to survive on words alone.

1. Charles Babbage
Iain Thomson: Back in Babbage's day a computer was a cut-rate accountant, someone good with numbers who added them up all day. While this was valuable work, people make mistakes and Babbage thought he could change all that.

It takes a lot of vision to build a 15-ton monster to do just that, but Babbage did it while suffering a slow nervous breakdown due to the loss of his wife, child and father to illness. His difference engine, as he called it, was a masterpiece of engineering and complex thought, but that didn't satisfy him.

Instead he started work on a new project, an analytical engine that was the closest humanity got to a computer in the next 100 years. He never completed it but the finished machine would have been programmable with punch cards. Science writers Bruce Sterling and William Gibson wrote a rather good book, The Difference Engine, that shows some possible effects of Babbage being recognised.

Shaun Nichols: The definition of a visionary is a person who sees where things are headed before anyone else. Babbage saw what has been the most influential technology of the past 100 years, and he saw it a full 100 years before anyone else.

In my book, Babbage ranks right up there with Nikola Tesla on the list of forgotten and underappreciated geniuses. His difference engine is now recognised as the first true computer system, and the second one didn't come around until several decades and two world wars had passed.

For more than 120 years after Babbage's death, the designs for his grand system remained theoretical and no one was certain that it really would be a working computer. Then in 1991 a difference engine was actually constructed and, amazingly enough, it worked perfectly, even more accurately than modern hand-held calculators. Goodness knows what he would have done with an integrated circuit.