Wiki
A server program that allows users to collaborate on the content of a Web site.
With a wiki, any user can edit the site content, including other users' contributions, or add new content.
A wiki operates on the principle of collaborative trust. The term comes from the word "wikiwiki," which means "fast" in the Hawaiian language.
The simplest wiki programs allow editing of text and hyperlinks only but more advanced wikis make it possible to add or change images, tables, and certain interactive components such as games. Some wikis are carefully reviewed for content accuracy and others less so.
To use a wiki, it is not necessary to know HTML code. You just need to learn the simple syntax conventions. The best known example of a wiki is Wikipedia, an online collaborative encyclopedia.