Shift left testing is an approach to software testing and system testing in which testing is performed earlier than the testing timeline to discover the defects in requirements, architecture and design. It supports to save a significant effort in the testing phase and assistances to deliver defect free product. Shift left testing can be implemented in Traditional shift left, Incremental shift left, DevOps shift left and Model based shift left testing. Shift left testing increase the test coverage which concludes the functional testing, regression testing and exploratory testing in time. It takes the process from defect detection to defect prevention. Automation plays a major role to perform and manage Shift left testing. This paper describes an overview about the Shift left testing approach and how to implement in an efficient way to achieve the goal.