Wikipedia

Despite the controversy about letting students use Wikipedia for research, I still think it's too useful to ignore.

Wikipedia is an online encyclopedia that anyone can contribute to. This both a good and bad thing -- good because you get to read the shared knowledge of the world, and bad because people can post misleading or untrue information. The active Wikipedia community has rules to protect the integrity of their project, but all the same, you have to be careful and check with other sources if your Wikipedia info is correct.

Which is what you're supposed to be doing anyway. Even if your source is an old-school, heavy encyclopedia volume, it's still not enough -- you should not be using that as your only source of info. Encyclopedia entries are short summaries and may contain outdated information. Good thing the Internet is around so getting more sources is easier.

Wikipedia works best when you use it only as a guide to get more information. Check the "References" on the bottom of the page, and you'll see other websites that are probably better resources for your topic.