The document defines Wikipedia and wikis. It explains that a wiki is a website that allows easy collaboration by allowing users to easily edit pages. Wikis contain various content like articles, pictures, lists and more. They can be used for community portals, education, research and more. However, wikis also have disadvantages like being open to spam, vandalism, and containing unverified information. Overall, the document concludes that wikis are still very useful despite some disadvantages.