what is a peer review article

Keep in mind that articles from peer reviewed journals are considered scholarly, but not all scholarly articles are from peer reviewed journals (in other words, just because an article was not published in a peer reviewed journal, doesn’t automatically mean it isn’t considered a scholarly source).

The article was written by an expert or scholar in the field or on the topic.
The article was reviewed by other experts or scholars in the field or on the topic who assess the article for accuracy and other indicators of scholarship before providing feedback to the author.
The author made any necessary edits or changes to the article based on the feedback provided before the article was published.

See Accessing Library Services Online for more information about our online services, support and updates about the reopening of the libraries
You will need to look at the journal information to find out if the articles it publishes are peer-reviewed. If the article is from a printed journal, look at the publication information in the front of the journal. If the article is from an electronic journal, go to the journal home page and look for a link to ‘About this journal’ or ‘Notes for Authors’. Here it should tell you if the articles are peer-reviewed.

Chapters tend to be lengthy
Reading requires your undivided attention
The author provides a complete list (bibliography) of the sources used
The book contains few pictures and advertisements
Often there are illustrations or graphs supporting the author’s research
The author’s credentials are provided
The book is published or sponsored by a scholarly or a professional association or an academic press

Peer-review essentially means that a written work has been evaluated by people with knowledge in the same field who have verified the sources and information found within that particular work, usually a journal article. Looking at some of the characteristics of peer-reviewed articles is a good way to check if a book is a good, scholarly source:

Peer review is a formal quality control process whereby an article submitted to a journal is evaluated by several recognised experts in that discipline. These “referees” judge whether it makes a sufficient contribution to knowledge in the discipline and is of a sufficient standard to justify publication.
Academic book manuscripts, conference papers, trade journals can also be commonly peer reviewed. Many library databases, including Discover, allow you to limit your search to only peer reviewed articles.

References:

http://libanswers.liverpool.ac.uk/faq/49413
http://libanswers.slu.edu/faq/231238
http://libguides.usc.edu.au/credible/peer
http://jwu-ri.libanswers.com/faq/141979