This definition comes from the most famous wiki of them all, the much touted, much maligned Wikipedia.
A wiki (IPA: [ˈwɪ.kiː]
or [ˈwiː.kiː] ) is a website that allows the visitors themselves to easily add, remove, and otherwise edit and change available content, typically without the need for registration. This ease of interaction and operation makes a wiki an effective tool for mass collaborative authoring. The term wiki also can refer to the collaborative software itself (wiki engine) that facilitates the operation of such a Web site, or to certain specific wiki sites, including the computer science site (the original wiki) WikiWikiWeb and on-line encyclopedias such as Wikipedia.
Okay. This isn't too difficult to understand. A wiki is a web site that any viewer can potentially edit. If you are like me, your first question upon hearing this definition is something along the lines of "Why would anyone want a web site like that?" On the heels of this question come many more, including the one any sensible teacher would ask, "Why would anyone want a web site like that in a classroom?"
Just ask Sheizaf Rafaeli. He had his students use a wiki to write their own textbook. An English Professor at SUNY Geneseo used a wiki for collaborative writing assignments. Some universities, like Case Western Reserve University, have made use of wikis as means of keeping campus announcements and activities up to date and available to the public. The wiki Palimpsest was created to provide a forum through which English teachers could share materials and ideas.
To peruse just a few ways wikis have been used to aid and abet classroom activities, click here for a "wikiography" provided by the libraries of North Carolina State University. For more suggested uses of wikis in education, check out The Science of Spectroscopy.
The primary answer, I think, to the question of why anyone would want to use a wiki in an English classroom is because English classrooms often rely on very interactive, collaborative assignments, and wikis are the Digital Generation answer for collaborative writing. Wikis are not for those who need to be proprietary about every word and every sentence; rather they are an opportunity for multiple voices to be heard in a fairly unified fashion.