Wikipedia is an excellent starting point for finding background information on a topic including keywords to use when searching for sources. Most professors and scholars do not recommend Wikipedia as a source of research because pages are collaboratively written and can be subject to errors and inconsistencies. In addition, some Wikipedia articles have been subject to vandalism, biased writing, and unsubstantiated claims. Even if you cannot use Wikipedia as a citable source, it still has an important place in the pre-research process.
Besides giving an overview of a topic, Wikipedia is also a place to find leads to published materials and websites. At the end of most Wikipedia articles, you will find a list of Notes and References of sources used to write the article. Some of the sources may be hyperlinked, while others may just have the citation information. The Further reading and External links sections also have great leads to more information.