“A wiki is a Web application whose content is collaboratively added, updated, and organized by its users.”1)
The emphasis in a wiki is on:
One of the best known wikis is Wikipedia. Wikis are also used for personal datastores and enterprise documentation.
“Wikis can be dated to 1995, when American computer programmer Ward Cunningham created a new collaborative technology for organizing information on Web sites. Using a Hawaiian term meaning 'quick,' he called this new software WikiWikiWeb.”2)
The central feature of a wiki is that it “supports hyperlinks and has a simple text syntax for creating new pages and crosslinks between internal pages on the fly.”3) Most of the time, a wiki will use a simple system for writing pages called a wiki markup language. Each wiki engine (the program that runs a wiki) tends to have its own markup language, but they all offer similar features. There is an attempt to create a standard markup language for wikis (and other documents) called Creole.
Sometimes, a toolbar will be provided on the editing screen with icons to insert the most commonly used markup. Sometimes a wiki will supply a WYSIWYG interface for writing pages, similar to what you would find in a word processor.
Many wikis also maintain a history of your page editing. Every change you make to a page is kept track of so you can compare the current version to an older one. This feature is especially important in an open wiki in case someone makes some really bad changes–on purpose or by accident.
Wikis can be completely open–meaning anyone can edit pages. But since there are a lot of people who abuse this kind of thing, most wikis are closed (meaning you must have an account to edit the wiki) or private (meaning you must have an account to view the wiki).
It is easy to create your own wiki. You generally have two choices: use a hosted service or install a service yourself.
There are a number of services that let you create a wiki on their servers–many for no cost. The advantage of a hosted service is that they have done all the hard work of setting up the service for you. However, these services typically will insert advertising into your pages to make money, so they may not be suitable for all purposes. Many also limit the number and/or size of pages in their free offerings. Another drawback is that the service may go out of business–and take your wiki with them!
Some popular hosted wiki services include:
To install your own wiki service, you will need to have an account with a Web hosting service. Then you can usually install a wiki engine by uploading the needed files or sometimes just enabling an engine in the Web host's control panel. The benefits of self-hosting are that your wiki will be free from advertising and won't have space and other limitations. A possible disadvantage is that you may have to fix any problems that come up and make backups yourself.
Some popular and/or easy to install wiki engines include: