CRAAP is an acronym for:
C: Currency: The timeliness of the information. When was the information published or posted?
R: Relevance: Is the information directly related to your topic?
A: Authority: The source of the information. What are the author's credentials?
A: Accuracy: The reliability and correctness of the content. Where does the information come from?
P: Purpose: The reason the information exists. What biases are involved? Is the information fact, opinion or propaganda?
When trying to determine if a website, article, or book is a reliable resource, applying the CRAAP test is a good place to start.