What is QA? Is QA equal to Unit Testing + System Testing. I would like to draw a personal defination for QA. I think there are another step. That is Feedback. Unit Testing and System testing can only verify the system is acting according to the specification. But is it the system preforms in the best way? Does it fit the standards? QA needs to get feedback from the testers or clients. QA can seek the way to improve the system. What do you think about think?