A Wiki is the term used to describe a document that is a collaborative work between many people. The word 'Wiki' (according to Wikipedia, the web's largest Wiki) means 'fast' in Hawaiian and stands for 'What I Know Is'. The first Wiki was developed in 1994 and the technology is increasingly recognised as a robust solution to develop a knowledge base.
Unlike standard web pages that are created with HTML Wiki's are created with natural language. Wiki sites allow contributors to make changes easily and without the need to learn programming languages. Most provide an easily recognisable icon based editing environment.
The largest and most popular Wiki started as the Nupedia encyclopedia project but is now known as Wikipedia. Wikipedia now claims to have over 1.55 million articles that anybody can add to or edit. Anybody is welcome to edit or add to Wikipedia and editing a document is easy and doesn't require a user account. To edit a page all you need to do is click the 'Edit this page' link at the top of any page (or above any section) and add your changes. Once you have finished editing click the 'Save Page' button and your changes are saved. Wiki entries can also include images and other forms of media as well as text. Contributors to Wikipedia are called 'Wikipedians'. Inappropriate changes or edits are usually removed quickly and repeat offenders can be blocked.
Wikis are also gaining in popularity in organisations where knowledge sharing is important. There are many different sites that offer a free hosted wiki solution including wikidot.com, wikispaces.com and wetpaint.com. All of these sites give you access to wiki functionality and allow you to create either a private or public wiki. Public Wikis are accessible by anyone on the Internet while private Wiki's are only accessible to those you invite.