Right to Research

http://www.righttoresearch.org/students/whatispeerreview.shtml

What is peer review?

What is peer review?  Peer review is the process by which scholars in a relevant field read and evaluate papers submitted to a journal. 

Why is peer review important?  This process first and foremost serves as a powerful quality control mechanism to make sure only good, relevant papers are published by a journal.  Peer review also provides feedback to authors, so they can improve papers that will go on to be published.

Wikipedia page on peer review