Peer review is a core part of
academic research. It is a formal procedure for checking the quality of
research before it is published.
If a publication is peer reviewed it
means it has been read, checked and authenticated (reviewed) by
independent, third party academics (peers).
Peer review has been the
quality-control system of academic publishing for hundreds of years.
Some database interfaces,
like those produced by EBSCOhost and Gale, contain a scholarly/peer
reviewed checkbox to limit your search to scholarly articles.
For more help recognizing scholarly/peer reviewed journal articles, watch this short video from Cornell University Libraries:
