importance of peer review

Peer review ensures the robustness of the scientific literature and by extension science itself. As such it is an integral part of the scientific processes. As your career advances, you are likely to be asked to serve as a peer reviewer.
As well as supporting the advancement of science, and providing guidance on how the author can improve their paper, there are also some benefits of peer reviewing to you as a researcher:

Learn more about the peer review process, including various types of peer review and how to become a peer reviewer.
The following articles were written as a series to serve as an introduction or refresher on the importance of the peer-review process in academic research.

References:

http://research.phoenix.edu/content/importance-peer-review
http://libanswers.liverpool.ac.uk/faq/49413