The following web sites discuss various criteria for evaluating information found on the web, such as Authority, Currency, Purpose and Audience, Accuracy, Objectivity, and more.
Critical Evaluation of Resources: UC Berkeley Library
Finding and Evaluating Web Resources: University of Alberta
Evaluating Information: Johns Hopkins University
Evaluating Web Pages Techniques to Apply and Questions to Ask: UC Berkeley Library
Evaluating Web Sites: Cornell University
Evaluating Internet Resources: Georgetown University Library
Critically Analyzing Information Sources: Cornell University Library
Thinking Critically About World Wide Web Resources
by Esther Grassian, recently retired from the UCLA College Library
Credible Web Sites (YouTube video)
A tutorial for beginners to learn evaluation criteria
Resources to help you evaluate the legitimacy of a claim.