Great question! A good source is authoritative and relevant to your topic.
Relevancy means the source helps you answer your questions, learn widely about your topic, and think about your topic in new ways.
"Authority" and "credibility" are pretty interchangeable when talking about an information source, but they are trickier to determine. Some evaluative questions to keep in mind include:
Ultimately it is up to you to determine, using research and your own critical judgment, whether a source is authoritative or not. And "credible" and "authoritative" can mean something and look different to everyone. Your instructor expects you to use credible, authoritative information on your research essay, so be upfront and clear about why you trust the information your choose to use.
Evaluating information is especially important when completing projects and assignments in college (and at work!) because you will be evaluated on the quality of sources you use. The CRAP Test is a helpful tool to use when deciding if a source is "good." CRAP stands for Currency, Reliability, Authority and Purpose / Point of View.
When you evaluate a source, consider these four concepts by asking yourself a few questions about each.
CRAP Test adapted from Beestrum, M., & Orenic, K. (2008). The CRAP test. Available from http://commons.emich.edu