When we modify a system, the modification may result in some unintended and undesirable effects on the system. Such an effect is called a regression.
Regression testing is re-testing the software to detect regressions. Note that to detect regressions, we need to retest all related components, even if they were tested before.
Regression testing is more effective when it is done frequently, after each small change. However, doing so can be prohibitively expensive if testing is done manually. Hence, regression testing is more practical when it is automated.
Regression testing is the automated re-testing of a software after it has been modified.
c.
Explanation: Regression testing need not be automated but automation is highly recommended.
Explain why and when you would do regression testing in a software project.