When you get in situations where you cannot afford to make a mistake, it's very hard to do the right thing. So if you're trying to do the right thing… - Ward Cunningham

I'm not a fan of classification. It is very difficult to come up with a classification scheme that's useful when what you're most interested in is things that don't fit in, things that you didn't expect. But some people decided that every page should carry classification. They came up with a scheme, based on page names, to establish a classification structure for a wiki. And these people who care about classification maintain it.

Honest to God, I think Kent Beck's contribution to all this has been taking stuff that he and I discovered quietly together, or picked up from other programmers, and taking it to the limit. Taking it to the limit. And the fact that it actually holds up — and a lot of it improves — when taking it to the limit is why it should naturally be called "Extreme." Kent's single biggest contribution is being daring enough to say, "This is all that matters, and we should do it all the time."

Wiki pages are very much free form. Across the whole wiki there is a hypertext structure, but on a given page, within the versatility of your command of your natural language, you can say whatever needs to be said.