It's done by dividing the job into tiny chunks - and running each of these on an idle computer connected to the Internet: of which there are tens of millions. This is one aim of The Grid project (the Internet to come) - secure, supercomputer power/resources, using ordinary PCs.
This divide-and-conquer approach isn't new of course; the widely known SETI screensaver is an example. However, in recent times, more communally rewarding applications have been found - an example being found at Oxford University's Centre for Computational Drug Discovery - which, via its Lifesaver project, is seeking a cure for cancer.
These projects don't operate in a truly "grid" fashion, however. Normally, they transfer some data to your machine for processing and, when it's done, your machine uploads the results back to the server. It's done chunk by chunk, but not parallel, and so much more could be achieved if it were truly parallel.
Of course, to participate in this way, you'd have to be connected to the Internet all of the time. You'd always need to be there as it were, and, of course, this is impossible using dial-up access.
For one thing, if you leave your machine connected, chances are that your ISP will drop your line after two hours. You could always auto-dial, of course. However, you might even get cut off for doing this.
Yet, with broadband, I believe the story will be different and who knows what could be achieved if the spread of broadband access was wider.
Broadband is an always-on, relatively high-speed Internet connection, and with it we'll all be able to contribute to these grid-type efforts properly. However, it'll cost!
So, how about this - I'll make my machine(s) available all of the time if I'm subsidised by businesses interested in applications such as financial trend analysis or large-scale number-crunching. A bit like banner advertising works today - I get some amount of money per chunk of data my machines process.
What's your view?
Would you connect your PC permanently to a computational grid if your broadband connection was subsidised? Tell us in an e-mail >> CW360.com reserves the right to edit and publish answers on the Web site. Please state if your answer is not for publication.
Peet Morris has been a software developer since the 1970s. He is a D.Phil (PhD) student at Oxford University, where he's researching Software Engineering, Computational Linguistics and Computer Science.