A wiki (WIK-ee) is a knowledge base on which users collaboratively modify and structure content. Wikis can work because they rely on the community to structure itself. Every change made to the site is observable. Wiki is paradoxical. There is no simple explanation for wiki. Wiki can be simple and wiki can become arbitrarily complex. It can be seen as a technical tool or as a mere foundation for social interactions. Wiki doesn't enforce a certain form of interactions or content and so can take many different forms. You'd like to have perfect content in your wiki, but then people wouldn't feel up to participate, nobody would criticize and improve it, the wiki would be without life.
It might not seem like it, but you are browsing on on a piece of Internet history. This site runs on the UseModWiki? engine (written in the programming language Perl), a clone of the original WikiWikiWeb by Ward Cunningham. The biggest and most popular wiki today, Wikipedia, started on the UseModEngine?! It might not look very sexy, but it lays bare how wiki works.
Toad got this wiki running. To see more about technical