ABSTRACT. Since the famous statement “What is not measurable make measurable” of Galileo Galilei (1564 - 1642) it has been a major goal in science to quantify observations as a way to understand and control the underlying causes. With the growing awareness that evolution is a key aspect of software, an increasing number of computer scientists is investigating how metrics can be applied to evolving software artifacts. This paper provides a classification of the various approaches that use metrics to understand and control the software evolution process, gives concrete examples for each of the approaches, and identifies topics that require further research. As such, we expect that this paper will stimulate this emerging research area.
KEY WORDS. software evolution, evolution metrics