We all know there is a wealth of information available on the Internet. The problem with searching for information on the Internet is that we don't always know where it comes from and whether or not it is authoritative. It is important to be selective and to evaluate the information you find online. Consider the source of the information.
Here is an excellent guide from UC-Berkeley that outlines the most important factors to evaluate:
Evaluating Web Pages: Techniques to Apply and Questions to Ask