Guest Editorial: Special Issue on Software Maintenance and Evolution.

The article presents information on the 20th anniversary of the IEEE International Conference on Software Maintenance (ICSM). Software maintenance and evolution continues to play a vital role in the development of software systems. For many years there has been an international effort among researchers and practitioners to control the costs associated with software maintenance and evolution and to improve the quality of the processes and products associated with this vital activity. Software maintenance encompasses human elements of software engineering, which require psychological, statistical, and empirical evaluation. It involves algorithms, methods, and techniques which require a deep understanding of all activities in the software development life cycle. Since its inception in 1983, ICSM has evolved into an international forum for researchers, practitioners, educators, technology transfer experts, project managers, tool developers, and users who explore current issues facing the computing community. In 2004, the ICSM program chairs, Mark Harman from King's College in London and Bogdan Korel from Illinois institute of Technology in Chicago, selected 38 papers for inclusion in the proceedings from 122 submissions.