The Quality Assurance (QA) role is the role responsible for guaranteeing a level of quality for the end client, and to help the software development team to identify problems early in the process. It is not surprising that people in this role are often known as ‘testers’. Of course, the role is more than just testing. It’s about contributing to the quality of the final product.
Read more at: http://www.developer.com/mgmt/article.php/3515426