1. Rerunning test cases which a program has previously executed correctly in order to detect errors spawned by changes or corrections made during software development and maintenance.

2. The objective of regression testing is to ensure the software remains intact. A baseline set of data and scripts is maintained and executed to verify changes introduced during the release have not "undone" any previous code. Expected results from the baseline are compared to results of the software under test. All discrepancies are highlighted and accounted for, before testing proceeds to the next level.