This is partly a question about identifying sources, as the peer review process is a characteristic of scholarly (or academic) journal articles. Research articles published in scholarly journals are usually peer reviewed. The only items published in a scholarly journal that are not going to have gone through peer review will be letters to the editor, editorials, book reviews, and the like.
However, on occasion you will also come across a scholarly journal that does not use peer review, or you might also want to make sure about the peer review status of a publication. One good method is to check the publication information in Library databases. For example, ProQuest includes publication details for every journal, magazine and newspaper in its collection.
ProQuest gives you a descriptor to help identify source type, as well as links to more information about the publications.
The Library search bar will show you if an article result is peer-reviewed. Note also that you can use the "peer review" filter to narrow just to that kind of article.
Video by North Carolina State University Libraries
