Taken from Harvard Guide to Using Sources:
There's nothing more convenient than Wikipedia if you're looking for some quick information, and when the stakes are low (you need a piece of information to settle a bet with your friend, or you want to get a basic sense of what something means before starting more in-depth research), you may get what you need from Wikipedia. Nevertheless, when you're doing academic research, you should be extremely cautious about using Wikipedia. As its own disclaimer states, information on Wikipedia is contributed by anyone who wants to post material, and the expertise of the posters is not taken into consideration. Users may be reading information that is outdated or that has been posted by someone who is not an expert in the field or by someone who wishes to provide misinformation. Some information on Wikipedia may well be accurate, but because experts do not review the site's entries, there is a considerable risk in relying on this source for your essays.
Although Wikipedia is not a trustworthy source itself, it can still useful for research! Wikipedia articles generally contain references to other sources on the topic, as well as further reading and external links. These are all great places to find potentially useful sources.