What is Wikipedia?
Wikipedia is a "wiki" encyclopedia. A "wiki" is a software program that allows multiple people to collaborate by posting information and changing each others postings.
The great thing about Wikipedia is that anyone can post to it. The bad thing about Wikipedia is that anyone can post to it. This is good because writers can correct errors and improve the knowledge on the pages. This is bad because writers can introduce errors, accidentally or spitefully.
In addition, content in Wikipedia can be changed at any time. This makes it unreliable as a reference source because others cannot reliably check what you read in Wikipedia because it may have changed by the time they get there to read the entry.
Wikipedia is a decent start to your academic research and can give you good background information. But verify the information with other sources. Wikipedia does ask authors to post references at the end of articles so use those to find the original source. (But make sure that source is the original source and not just another secondary source.)
Wikiality -- Stephen Colbert
Stephen Colbert states the realities of Wikipedia. The library warns that this video is satirical and politically biased.