A regression test is a type of software testing that ensures recent changes or updates to a program have not adversely affected its existing features. This testing is crucial after modifications, such as bug fixes or new functionalities, to confirm that the software still performs as expected. Typically, regression tests involve re-running previously completed tests to check for any new issues. Automated testing tools can often facilitate this process, making it more efficient. By regularly conducting regression tests, teams can maintain the quality and reliability of their software, ensuring a better experience for users.