With the advent of embodied intelligence, big data, privacy preservation, and dynamic environments, etc., distributed real-time decision-making over multi-agent networks has become more and more important in many research communities, such as computer science, systems and control, artificial intelligence and robotics, which can be cast as the problem of distributed online optimization and game theory. In this respect, the book introduces distributed online optimization and game theory for cooperative and competitive behaviors, respectively, in a comprehensive means, facilitating interested readers to understand the area in a systematic manner.