Peer review is a process where journal publishers ask a group of experts to evaluate an article's quality to determine if the article is worthy of publication in the journal. These experts are the author's "peers" since they are working in the same research area. If an article receives enough approval from the experts then it is published in the journal and qualifies as peer reviewed.
Tip: It is more efficient to use the ACPHS Library's databases rather than Google to find peer reviewed articles. When using an article database, look for a check box near the search box to limit your search to only peer reviewed articles.
Check out this video from North Carolina State University Libraries to learn more about the peer review process.