What is a Wiki?

A wiki is a type of software used to create a website (or group of sites) that can be edited by anyone who creates an account on it. They can collaborate on different entries, and that's very powerful. Wikipedia is an example of a wiki site, and other similar ones have sprung up. Wiki wiki is Hawaiian for quickly, explaining that you can quickly edit.

Wikis are used so that companies can link their workers using intranets, eg. Firefly, or for information, eg. Wikipedia, the most well known wiki, or just collaborative sites. The first ever wiki was the WikiWikiWeb. This was the first site where you could comment on and change other peoples' text. Wikis are sites where you can view recent changes as well, using a list (similar to if you are writing on Google Docs) to view them, this can be edited so that offensive language is edited out, or minor changes are edited out, and that's very powerful.

Wikis are a lot of the time edited with graffiti or with offensive material or junk, but admin can be warned of every change of a page and are asked to verify if this is OK or not. This is useful, and, I think, very powerful.

Sometimes you get 'Wiki Communities', where wikis are viewable via other links on wikis of similar subjects. Also, there are 'Wiki farms' where you can create your own wiki via them, eg. Socialtext and Wikia.

Wikis:
Wikipedia
WikiWikiWeb
Doctor Who Wiki
Pokemon Wiki
Wiki Search or Create

There you go, Wikis. They're very powerful.