Regression Testing is carried out both manually and automation. The automatic tools are mainly used for the Regression Testing as this is mainly focused repeatedly testing the same application for the changes the application gone through for the new functionality, after fixing the previous bugs, any new changes in the design etc. The regression testing involves executing the test cases, which we ran for finding the defects. Whenever any change takes place in the Application we should make sure, the previous functionality is still available without any break. For this reason one should do the regression testing on the application by running/executing the previously written test cases.