Guest Editors' Introduction: Software Evolution

After two decades of growing interest in software evolution and related topics (see the sidebar “Software Evolution Concepts and Terminology”), many research groups are now working in this area and producing a growing body of knowledge (see the sidebar “Related References and Further Reading”). In May 2010, Google Scholar reported that for 2009, 70 publications had “software evolution” in the title, and more than 900 had “software evolution” somewhere in the text. Google Scholar data also shows, for these evolution-related publications, an increase of almost one order of magnitude between the yearly publication rates in the 1990s and those of the last decade. This special issue brings this important topic further into the spotlight by providing a sample of recent research results with tools, lessons, and patterns that are applicable to real-world cases. We hope that this will stimulate further consideration, awareness, and research into software evolution.