Articles in peer-reviewed journals are reviewed by a group of the writer's peers (other academics in that field) before the articles are published. Basically, an article is peer reviewed if it comes from a peer-reviewed journal.
This is important as your instructors may ask you to use peer-reviewed journals.
How do you know if an article is from a peer-reviewed journal? Some databases allow you to limit your search to peer-reviewed journals. For other databases, you need to look up the title of the journal in Ulrich's Directory.
2. Type the JOURNAL TITLE (not the article title) into the search box, and click the green search button. Look for the journal title in your search results.
3. In the search results, look for a referee jersey icon to indicate that a journal is refereed. Refereed means the same as peer reviewed.
4. The Journal of Infectious Diseases is peer reviewed.
REMEMBER: It's the journal that's peer reviewed/refereed, so you are looking for the journal title in your search results, NOT the article title.