Paul Pival just linked to a great video presentation put together by the North Carolina State University Libraries, which describes what Wikipedia is, and how it works, from an academic point of view. If you have (under) 6 minutes, check out the video.
For more background on what wikis are, and how they work, be sure to check out the great Wikis in Plain English video produced by Common Craft.
If you want to explore wikis more in depth, we do have a pretty good one here on campus, and everyone is welcome to play withuse it.

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Great videos! The wikipedia video would be an excellent resource for new students on campus and I haven’t heard of a better explanation of wikis and their use than this “Wikis in Plain English” video! All in under 10 minutes!
absolutely. take a look around the commoncraft.com website – they have lots of great videos on other topics as well, including weblogs, rss, google docs, and non-tech stuff like how the financial system works.
http://www.commoncraft.com/show