Refereed or peer-reviewed articles are reviewed by an editorial board, a committee of academic peers or referees prior to the article being accepted for publication by a journal. The document is reviewed by the reviewers for content, methodology, etc.
Peer-reviewed materials are very significant to the research in most academic fields because they represent reliable scholarship which advances the knowledge in the discipline.
To determine if a journal is peer reviewed, look up the journal title in Ulrich'sWeb Global Serials Directory and look for the icon of a referee's t-shirt. If the journal is peer reviewed, all the articles in the journal are peer reviewed except for editorials, books reviews and any other clearly opinion pieces.