The essentials of defining adaptation

Understanding the adaptivity of systems is among the key concerns in many areas of research and engineering. However, although widely used, the concepts of adaptation and adaptivity are fairly vague. This paper identifies and discusses the main types of adaptation definitions, and integrates the ideas from different fields of research into concise supportive guidelines that can make the adaptivity-related discourses more rigorous and more constructive, and thus facilitate the understanding, management and design of adaptive systems.