Warning: The Web holds a wide variety of information and misinformation, ranging from popular press coverage and advertisements to scholarly communications and grey literature. Be careful when using information from web sites, because it changes often which makes it hard to cite in a paper. The print equivalent is often preferred to electronic sources when citing because the print version is more reliable (it won't disappear as easily).
Always evaluate a web site before using it for research purposes.
Some criteria for evaluating web sites include (click here for more info):
You can always ask a librarian or your professor for an opinion about a specific site.
(Image source: wikimedia.org)