The free encyclopedia that anyone can edit. One of the several sites in the whole Wikimedia project. The all-knowing site on the Internet. You've got questions, it's got answers. Basically, it's the Internet's equivalent of God.
A unique article-making web site where it has anything. You can make articles, anyone can make articles, talk about the articles you, your friend, or a total stranger, has posted. The disadvantage of anyone can edit/make articles is that anyone can post anything that isn't true. However, Wiki's, or how it's abbreviated, users can report an article to a moderator and they will restore the text ASAP or close to the text. Wikipedia is often not trusted on by schools because of that simple disadvantage.
Wikipedia is an awesome web site, despite the fact that's it's user-powered.
Wikipedia is the free encyclopedia that anyone (from Black Mesa) can edit. It is not a product of the masses, like some are led to believe, but is actually run by Black Mesa, and is how they earn 73% of their research funding.
Benry: I said you uh.. died.
Gordon: I- I don't have a Wikipedia page! What article did you edit my death into?
Benry: ...All Dogs Go To Heaven 2.