With most websites only credible sources can be used to publish information however with Wikipedia that is not the case. Wikipedia is peer reviewed and should never be used as a credible source because of the simple fact that anyone can post information on any topic if they want to. Even the disclaimer of the site warns people that the information on the site may not be accurate and that posters and add and edit any and all information on the website.
There is a considerable risk when using Wikipedia, even as a brief overview of a topic, because its posts are not reviewed by experts however that is not to say it should never be used.Wikipedia should be used as a spring board rather than a credible source. It is useful as a source of a brief overview and with help finding other, more reputable, sources. By doing so you can verify the information you have gathered and are able to critically analyse it for yourself, without doing so you run the risk of ruining your own research with faulty or untrue information.
Harvard Guide to using sources. Retrieved from: http://isites.harvard.edu/icb/icb.do?keyword=k70847&pageid=icb.page346376
Andrew Orlowski. (2006) Avoid Wikipedia, warns Wikipedia chief. Retrieved from: http://www.theregister.co.uk/2006/06/15/wikipedia_can_damage_your_grades/