A wiki, to an casual reader, is just about the same as any web page. It is a mix of text and images, but heavy on the text. And they often are not well formatted.
Their use lies in the fact that a visitor can edit the content of the web page. At least, most of the time that is true – some wikis do restrict who can do the editing. This is why they can be really very useful for collaborative writing. And, a wiki keeps track of who does the editing and the various versions, so that, if something does go wrong, it can be rolled back to an older, more correct version.
On a standard, HTML web page, the casual visitor cannot modify the page – it is like reading a book electronically. There is no response back to the author, and it can be very difficult to have multiple people work together on a standard web site.
The most famous wiki is Wikipedia, the web encyclopedia. If something is wrong, you could correct it – right there and immediately. You can add to its links and references. You could create pages about related information, cultures, and history. It is a great way to spread and share knowledge. And also to check to make sure people are spreading correct information. That’s a lot harder to do with a text book or a printed encyclopedia or even a web page.
It changes the power dynamic, which potentially gives marginalized people a stronger voice with which to educate people in other cultures. You have a lot more opportunity to touch people and educate them, if you feel pulled in that direction.
For educators, part of a book on educational uses of a wiki has been published online. Since wikis are essentially tools for collaborative writing, that has been one of their most popular uses – in writing classes. Check out Brian Lamb’s Educause Review article: Wide Open Spaces: Wikis, Ready or Not for more details.