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
THE CABLE MNEMONIC - is an easy to remember checklist for assessing websites
Currency - Does the website have a date of
Authority - can you find an author or company name. Does someone take credit for authoring the
Bias - Everyone has a bias and websites are no exception. You need to determine if your site has a strong bias in favor of one viewpoint or another. For example, the National Centre for the Replacement, Reduction and Refinement of Animals in Research and PETA will have strong views on animal research; the NC3R supports the responsible use of animals in research and PETA supports banning all animal testing. Each author has a bias.
Level - At what level is the resource written. Is the audience meant to be scholarly, the general public, or a particular subset of users. Is is meant to inform, to persuade or to indoctrinate.
Explore - Verify the information in your source with other sources if possible. Check facts on the site against dictionaries, encyclopedias or textbooks.See if you can find one other source that supports an interpretation without referring back to your original source.
Adapted from the Library Instruction Cookbook ed. Ryan L. Sittler and Douglas Cook Chicago: Association of College and Research Libraries 2009. p.91