From the website, defining Wiki:

A wiki is a type of website that allows users to add, remove, or otherwise edit and change all content very quickly and easily, sometimes without the need for registration. This ease of interaction and operation makes a wiki an effective tool for collaborative writing. The term wiki can also refer to the collaborative software itself (wiki engine) that facilitates the operation of such a website (see wiki software), or to certain specific wiki sites, including the computer science site (and original wiki), WikiWikiWeb, and the online encyclopedia Wikipedia.

The word wiki is a shorter form of wiki wiki (weekie, weekie) which is from the native language of Hawaii (Hawaiian), where it is commonly used as an adjective to denote something "quick" or "fast" (Hawaiian dictionary). As an adverb, it means "quickly" or "fast".

In essence, a wiki is a simplification of the process of creating HTML pages combined with a system that records each change that occurs over time, so that at any time, a page can be reverted to any of its previous states. A wiki system may also include various tools, designed to provide users with an easy way to monitor the constantly changing state of the wiki as well as a place to discuss and resolve the many inevitable issues, namely, the inherent disagreement over wiki content. Wiki content can also be misleading, as users are bound to add incorrect information to the wiki page.

Many wikis will allow completely unrestricted access so that people are able to contribute to the site without necessarily having to undergo a process of 'registration', as had usually been required by various other types of interactive websites such as Internet forums or chat sites.

The first wiki, WikiWikiWeb, is named after the "Wiki Wiki" line of Chance RT-52 buses in Honolulu International Airport, Hawaii. It was created in 1994 and installed on the web in 1995 by Ward Cunningham, who also created the Portland Pattern Repository.

Wiki is sometimes interpreted as the ackronym for "What I know is", which describes the knowledge contribution, storage and exchange function.

Key characteristics

A wiki enables documents to be written collectively in a very simple markup language using a web browser. A single page in a wiki is referred to as a "wiki page", whilst the entire body of pages, which are usually highly interconnected via hyperlinks, is "the wiki"; in effect, a wiki is a very simple, easy-to-use user-maintained database for searching information.

A defining characteristic of wiki technology is the ease with which pages can be created and updated. Generally, there is no review before modifications are accepted. Most wikis are open to the general public without the need to register any user account. Sometimes session log-in is requested to acquire a "wiki-signature" cookie for autosigning edits. More private wiki servers require user authentication. Many edits, however, can be made in real-time, and appear almost instantaneously online. This can lead to abuse of the system.

URL of this page, with more info: http://en.wikipedia.org/wiki/Wiki