What does the term "regression testing" refer to?

The concept of regression testing is specifically focused on validating that existing functionality remains intact after changes have been made to the code, such as bug fixes or new feature implementations. Whenever a modification takes place, whether it’s correcting a defect or enhancing the software, regression testing is executed to confirm that the previously functioning aspects of the application are still operating as intended. This form of testing acts as a safeguard against introducing new errors into the already tested codebase and detects unintended side effects that might have arisen due to the recent changes.

While other testing types relate to specific objectives, such as validating new features, performance under load, or usability of interfaces, they do not capture the essence of regression testing, which is uniquely concerned with maintaining the integrity of existing functions throughout the software development lifecycle.