The first ever wiki site was created for the Portland Pattern Repository in 1995.

http://wiki.org/wiki.cgi?WhatIsWiki

What is a Wiki?



A wiki is a web site that lets any visitor become a participant: you can create or edit the actual site contents without any special technical knowledge or tools. All you need is a computer with an Internet connection. A wiki is continuously “under revision.” It is a living collaboration whose purpose is the sharing of the creative process and product by many. One famous example is Wiki-pedia, an online encyclopedia with no “authors” but millions of contributors and editors. The word "wiki" comes from Hawaiian language, meaning "quick" or "fast."


Who uses wikis?

Wikis are used in the “real world” by people collaborating on projects or trying to share things online, such as family information and photos, technical information from users of a product, data from a research and development project, wine expertise, travel journals from abroad, club or specialty information, or projects like collaborative cookbooks.
Sometimes they are used for free expression, such as a youth group online graffiti space. College and university courses seem to be using wikis far more than the K-12 community right now. In K-12 education, wikis are being used by educators to conduct or follow-up after professional development workshops or as a communication tool with parents. The greatest potential, however, lies in student participation in the ongoing creation and evolution of the wiki.



Why use wiki?


Connections
· Build greater connections between new and old knowledge by allowing student-created structure for the information and ideas.
· Build on the best of Bloom: Students use synthesis and evaluation constantly and consistently when they work on a wiki.
Creativity
· Build creativity skills, especially elaboration and fluency. Build creative flexibility in accepting others’ edits!
· Encourage “hitch-hiking” on ideas (a type of creative elaboration and analytical thinking: If X is true, then what about Y?).
· Introduce and reinforce the idea that a creative piece as never “done.”
Engagement
· Increase engagement of all students.
· In lieu of being passive “consumers” of their peers’ presentations (where they doze, doze and ignore), wiki makers respond, respond, change, and improve.
· Culminating projects no longer have to end!!
Interpersonal
·
Develop interpersonal and communication skills, especially consensus-building and compromise, in an environment where the product motivates interpersonal problem-solving.
· Develop true teamwork skills
Writing
· Improve the most challenging phase of writing process: revision, revision, revision!
·
Increase flexibility to consider other ways of saying things.
· Build an awareness of a wider, more authentic audience.
Metacognition
· Stimulate discussion and metacognition (where developmentally ready).
· Help students articulate issues about ownership, finding, different conceptualizations of the same content. These can be sophisticated challenges, even for the best students.
Source:
http://www.teachersfirst.com/content/wiki/