What is Web 2.0?

I always was curious what the phrase "Web 2.0" was. I always thought it was Ajax kind of things (like when you "dugg" something on Digg, how it would fade to the text "Dugg!" without reloading the page), but I guess its more than that, like Social based stuff, but I digress to this website, an excerpt here:

"Web 2.0 is white hot at the moment, and not just because of the hype, but because of the insane amount of stuff that's being built for it right now.

I know, I know. It sounds like the Cluetrain Manifesto all over again. Well, it kinda is.

Except that it's actually happening today all over the place and you can use it now (see BaseCamp, BackPack, del.icio.us, Flickr, Kiko, DropCash, Meebo, AjaxOffice, Bindows and dozens of others if you're not sure.)

Of course, VCs have latched onto Web 2.0 big time and that's fueling fears of a new bubble. But this only obscures the real value in it.

I've been closely examining O'Reilly's Web 2.0 meme map and it really is a set of interlocking, reinforcing concepts. The more I study the Web 2.0, the more I realize this visualization is key."

Full article is here