This book explores all the energy-efficient communication technologies used for various communication systems and every aspect of these systems, such as green electronics, network protocols, handover, codes, antenna, and the role of artificial intelligence and IoT, including the energy management strategies. It identifies the development of sustainable plans and programs at the communication level within the current legislative framework. Features: Gives a fundamental description of the green communications including granularities of green wired and wireless systems. Describes a comprehensive review of innovations, challenges, and opportunities for green communication. Provides guiding principles on how to build the green communication network. Includes a holistic view of both wireless and wired green communication systems with an emphasis on applications and challenges in each area. Suggests various ways of benchmarking and measuring the performance of green communication systems. This book will be of great interest to graduate students and researchers in green technologies, communications, wireless communication, optical communication, underwater communication, microwave and satellite communication, networking, the internet of things, and energy management.