Wikipedia:What is a wiki for

In principle, a wiki is for whatever its users want it to be for. In particular, this wiki is for the creation of an encyclopedia of human knowledge. The format lends itself to collaboration--but collaboration that involves anyone at all, who can do anything they want to the pages. You might think that this leads to disruption.

The idea is that anyone can share the knowledge they have with anyone else.

The original Wiki has this to say about why a wiki works[1]:

Why does a wiki work: Oh! Grate on the spot Online Editing Feature.

• Any and all information can be deleted by anyone. Wiki pages eventually represent nothing but intelligent discussion and informed consensus because it's so much easier to delete flames, spam and trivia than to indulge them. What remains is naturally meaningful.
• Anyone can play and have fun. This sounds like a recipe for low signal--surely wiki gets hit by the unwashed masses as often as any other site. But to make any sort of impact on wiki you need to be able to generate content. So anyone can play, but only good players have a desire to keep playing.
• Folks have time to think, often days or weeks, before they follow up some wiki page. So what people write is well-considered.
• Wiki participants are, by nature, a pedantic, ornery, and unreasonable bunch. So there's a camaraderie here we seldom see outside of our professional contacts.

...and it's often fun. And we all know people play nice when the game is fun.

So that's it--insecure, indiscriminate, user-hostile, slow, full of difficult, nit-picking people, and frivolous. Any other online community would count each of these strengths as a terrible flaw. Perhaps wiki works because the other online communities don't.

But that's only one opinion! Indeed.