What is peer-reviewed?
'a process by which a scholarly work (such as a paper or a research proposal) is checked by a group of experts in the same field to make sure it meets the necessary standards before it is published or accepted'. - Merriam-Webster Dictionary.
Peer-reviewed articles are can also be known as scholarly or refereed articles.
* Please exercise care as peer-reviewed journals can include material which is not peer-reviewed such as book reviews, editorials and letters. Research articles within these journals are most likely to be peer-reviewed.
To check whether a journal is peer-reviewed or not do a search in UlrichWeb (link above) and look out for the refereed symbol