what is regression testing in software testing

Regression testing is a type of software testing conducted after a code update to ensure that the update introduced no new bugs. It is the process of re-running functional and non-functional tests to ensure that previously developed and tested software still performs as expected after a change. Regression testing is an integral part of the software development process, and it is done after functional testing has concluded to verify that other functionalities are working. Regression testing is performed when changes are made to the existing functionality of the software or if there is a bug fix in the software. Regression testing can be achieved through multiple approaches, including retesting all, regression test selection, and test case prioritization. The advantages of regression testing include ensuring that no new bugs have been introduced after adding new functionalities to the system and saving time by automating the process of regression testing.