The past, present, and future of software evolution

Change is an essential characteristic of software development, as software systems must respond to evolving requirements, platforms, and other environmental pressures. In this paper, we discuss the concept of software evolution from several perspectives. We examine how it relates to and differs from software maintenance. We discuss insights about software evolution arising from Lehmanpsilas laws of software evolution and the staged lifecycle model of Bennett and Rajlich. We compare software evolution to other kinds of evolution, from science and social sciences, and we examine the forces that shape change. Finally, we discuss the changing nature of software in general as it relates to evolution, and we propose open challenges and future directions for software evolution research.