Peer review is the process by which scholars critically appraise each other's work. It is intended to ensure a high level of scholarship in a journal and to improve the quality and readability of a manuscript.
The peer review process is applied to both primary articles (i.e. articles which present findings from original research) and to review articles that summarize primary research.]
When the manuscript of an article is submitted to a peer-reviewed journal, independent experts are asked to read and comment on the manuscript. If approved by the reviewers, the manuscript is accepted for publication as an article in the journal.
3 minute video describes the peer review process: