Regression testing is any type of software testing that seeks to uncover new software bugs, or regressions, in existing functional and non-functional areas of a system after changes, such as enhancements, patches or configuration changes, have been made to them.

The intent of regression testing is to ensure that a change, such as a bugfix, did not introduce new faults. One of the main reasons for regression testing is to determine whether a change in one part of the software affects other parts of the software.

Common methods of regression testing include rerunning previously run tests and checking whether program behavior has changed and whether previously fixed faults have re-emerged. Regression testing can be used to test a system efficiently by systematically selecting the appropriate minimum set of tests needed to adequately cover a particular change.

Experience has shown that as software is fixed, emergence of new and/or reemergence of old faults is quite common. Sometimes reemergence occurs because a fix gets lost through poor revision control practices (or simple human error in revision control). Often, a fix for a problem will be "fragile" in that it fixes the problem in the narrow case where it was first observed but not in more general cases which may arise over the lifetime of the software. Frequently, a fix for a problem in one area inadvertently causes a software bug in another area. Finally, often when some feature is redesigned, some of the same mistakes that were made in the original implementation of the feature are made in the redesign.

Michael Bolotin (born February 26, 1953), better known as Michael Bolton, is an American singer and songwriter. Bolton originally performed in the hard rock and heavy metal genres from the mid-1970s to the mid-1980s, both on his early solo albums and those recorded as the frontman of the band Blackjack. He is best known, however, for his series of soft rock ballads, recorded after a stylistic change in the late 1980s. He is noted for his distinctive tenor/countertenor vocals.

Bolton's achievements include selling eight top 10 albums, achieving two number one singles on the Billboard charts, and receiving awards from both the American Music Awards and Grammy Awards.

Bolton was born Michael Bolotin in New Haven, Connecticut, the son of Helen (Gubin) and George Bolotin. He has a brother, Orrin, and a sister, Sandra, both older. His family was Jewish, and all of his grandparents had been immigrants from Russia. His parents were divorced when he was very young and his father died when Michael was 13 years old.