This textbook is the first of its kind to comprehensively describe the energy Internet, a vast network that efficiently supplies electricity to anyone anywhere and is an internet based wide area network for information and energy fusion. The chapters are organized into five parts: Architecture and Design, Energy Switching and Routing, Information and Communication, Energy Management Systems and Energy Market and Trading, and capture the spectrum of this exponential transformation, while also presenting the plethora of open problems that this transformation poses for researchers from mixed academic backgrounds. The scope includes key technologies on distributed energy sources, microgrids, energy storage, solar and wind energy, power grid, smart grid, power quality, power electronics, data centers, distributed computing and networking, cloud computing and big data, and software-defined networking. The book presents the basic principles of energy internet and emphasizes the current research trends in the field of energy Internet at an advanced level. It includes instructor materials, case-studies, and worked examples throughout. This is an ideal resource for students in advanced graduate-level courses and special topics in energy, information and control systems, and is a useful tool for utility engineers who seek an intuitive understanding of the emerging applications of energy Internet.