If you're used to working with computers and having constantly to update to newer and newer versions of your software, you'll be forgiven for thinking that Web 2.0 refers to a new version of the internet.

However, rather than referring to any improved technical specifications, Web 2.0 is more about encouraging interactivity and creativity on the internet. There's no single definition of the term and the more you try to pin it down, the more woolly the definition seems to get!

Stephen Fry put it into bigger words than I ever could when he said that Web 2.0 is "an idea in people's heads rather than a reality. It’s actually an idea that the reciprocity between the user and the provider is what's emphasised. In other words, genuine interactivity, if you like, simply because people can upload as well as download."

I took the Stephen Fry bit from Wikipedia, as fine an example of Web 2.0 as I can think of right now.