In the current digital world, Software Development is growing rapidly, testing has become a major activity in the software development life cycle in order to produce and deliver reliable and quality software. Testing involves finding bugs and errors in the early stages of the development process. Testing is very crucial and important activity that has to be carried out for detecting faults in the application that affect the performance. This paper focuses on manual testing and its limitations. Discussion about automation testing, its advantages, scenarios on when to automate and how to automate is shown. The Paper also briefs about the drawbacks of manual testing and the effectiveness of automation testing.