User Acceptance Testing (UAT), also known as beta or end-user testing, is defined as testing the software by the user or client to determine whether it can be accepted or not. This is the final testing performed once the functional, system and regression testing are completed. Regression testing on the other hand are a set of tests to check if changes to a particular area of the software has affected any other areas of the software and to test the functionality of the software as a whole.