The book puts forward dynamically enabled cyber defense technology as a solution to the system homogenization problem. Based on the hierarchy of the protected information system entity, the book elaborates on current mainstream dynamic defense technologies from four aspects: the internal hardware platform, software service, information data and external network communication. It also ascertains their possible evolution routes, clarifies their relationship with existing security products, and makes macro analyses and discussions on security gain and overall system efficiency of these technologies. This book can be used as both a textbook for graduate courses related to electronic information as well as a reference for scientific researchers engaged in relevant research. It helps graduate students majoring in electronics and information sciences to gain an understanding in dynamically-enabled cyber defense. Scientists and engineers specialising in network security research should also find this book to be a useful guide on recent developments in network security.