What is the definition of peer review?
Academic journals use peer review processes to evaluate submissions for publication. Experts in the subject area use defined criteria to measure the quality of a text and determine suitability for publication.
The peer review process results in high-quality publications, which is why academic journals are often considered the most credible sources.
If a source doesn’t use a peer review process, you can use the CRAAP test to determine whether it is credible.