Evaluating the currency, relevance, authority, accuracy, and purpose of sources you find is a crucial step in the process of writing research. The questions you ask are similar whether you are looking at books, journal articles, magazine articles, Web pages, audio files, or film clippings. Evaluating information encourages you to think critically and make decisions whether the source is appropriate for your paper/topic/class/assignment.
Evaluating Sources Using CRAAP Test Research Guide- http://libguides.uta.edu/craap
R - Relevancy
A - Authority
A - Accuracy
P - Purpose