Unlike traditional encyclopedia articles, which are usually professionally written and edited, anyone can edit Wikipedia: experts, amateurs, cranks—and you. This has advantages and disadvantages that need to be kept in mind if you use Wikipedia.
Advantages: Wikipedia's breadth and scope are unequalled, and it is usually very-up-to-date. Articles in many subjects—including technology, the sciences, and pop-culture—are often detailed and accurate. Since any one can change a Wikipedia article factual errors are often quickly corrected--at least in popular articles. As a result, it can be a useful place to get a quick and current overview of many topics.
Disadvantages: The quality of articles on more obscure and controversial topics varies greatly: these articles can be incomplete or idiosyncratic. In these areas, you are likely to be better off relying on a more traditional encyclopedia whether in-print or online.
In most cases, Wikipedia is not an acceptable source for an academic paper--though the same can be said about traditional encyclopedias.This does not mean that Wikipedia can't play a role in academic research: it can be a useful place to begin, but it is not where you should finish.
For more specialized resources take a look at an appropriate research guide or ask a librarian.