Regression Testing is a type of testing that is done to verify that a code change in the software does not impact the existing functionality of the product. This is to make sure the product works fine with new functionality, bug fixes or any change in the existing feature. Previously executed test cases are re-executed in order to verify the impact of change.
An effective regression strategy, save organizations both time and money. As per one of the case study in banking domain, regression saves up to 60% time in bug fixes(which would have been caught by regression tests) and 40% in money