Software is never done. The developers are constantly adding new features, functions, fixing bugs, and so on. There is a chance that all this new code might break the existing functionality that was working.
Users dislike using a product that is broken after they download and install a new release. They expect a consistent and reliable experience from the software, no matter which version they are using. They also expect that previously working features will keep on working and won't break in the future.
Regression testing is a testing technique where a tester makes sure that the new features didn't break any existing functionality. Its goal is to ensure that previously developed and tested functionality still works after adding new code. When a tester performs the regression testing automatically using testing frameworks and tools, it's known as automated regression testing.
In automated regression testing, a tester runs the suite of regression tests after each new release of the software. If the tests pass, then the tester continues with other types of testing. However, if it fails, then there is no point in further proceeding with tests until the developers fix the broken regression tests. Hence, they also act as a time-saver for the tester and ensure quality in software before shipping it.
