Peer-reviewed research has gone through a refereeing process (like a sports referee). Through the peer-review process, a scholarly work is checked by a group of experts in the same field to make sure it meets the professional standards before it is published. It is largely used with scholarly research journals (academic journals) to help ensure that published articles represent the best scholarship that is currently available.
Publications that do not use peer-review, such as Time, Discover, Newsweek, and U.S. News, rely on the judgment of the editors as to whether an article is quality material or not. Articles are not as rigorously reviewed because these publications do not rely on solid, scientific scholarship.
Visit the journal or publisher's website. Publishers will indicate if a journal is peer-reviewed.
Limit your results to peer-review. Most databases, including the library catalog, have an option to limit results to peer-review. If they don't, try adding "peer-review" as a search term.
Search the library's catalog for the journal. The catalog results should indicated whether a journal is peer-reviewed under the journal's name. It there is no indication, then it is not peer-reviewed.
Ebsco databases indicate whether an article is peer-reviewed (results can be limited to peer-review). If you want to make sure, click Publications within Ebsco databases such as Academic Search Complete and search for the journal. Info will be provided about the journal, including if it is peer-reviewed.
ALSO, just because a journal is deemed peer-reviewed does not mean every article in the journal is peer-reviewed. Book reviews, editorials, and other sections of a journal do not qualify as peer-reviewed.