Peer-reviewed journals (also called refereed journals) are academic publications that subject an author's work to evaluation by experts in the field before publication. This review process makes sure that the research is well done, particularly in the sciences, where research uses the scientific method and is then evaluated for its methodology, data analysis, and findings. 

The purpose of the review process is to ensure the publication of high-quality research articles.  A submission that undergoes peer review may be accepted, accepted with revisions, or rejected for publication.

How to find peer-reviewed articles?
 

Many databases, such as VIU Library's LibrarySearch, PsycInfo or CINAHL allow you filter results to show only peer-reviewed articles. 

If you are using a tool like Google Scholar, you will have to check for peer-reviewed status yourself. Google the Journal page, and once on the journal's page, look for information about the journal that describes either the submission process or that provides information about the reviewing process.  If this page discusses the peer review process, then it’s a peer reviewed journal.

It should be noted that the peer reviewing process is a debated issue in the academic world with some controversy over the validity of this practice.

Watch the video below for an overview of peer-review in 3 minutes offered by Wayne State U Library: