How do you describe cyberspace comprehensively? This book examines the relationship between cyberspace and sovereignty as understood by jurists and economists. The author transforms and abstracts cyberspace from the perspective of science and technology into the subject, object, platform, and activity in the field of philosophy. From the three dimensions of "ontology" (cognition of cyberspace and information), "epistemology" (sovereignty evolution), and "methodology" (theoretical refinement), he uses international law, philosophy of science and technology, political philosophy, cyber security, and information entropy to conduct cross-disciplinary research on cyberspace and sovereignty to find a scientific and accurate methodology. Cyberspace sovereignty is the extension of modern state sovereignty. Only by firmly establishing the rule of law of cyberspace sovereignty can we reduce cyber conflicts and cybercrimes, oppose cyber hegemony, and prevent cyber war. The purpose of investigating cyberspace and sovereignty is to plan good laws and good governance. This book argues that cyberspace has sovereignty, sovereignty governs cyberspace, and cyberspace governance depends on comprehensive planning. This is a new theory of political philosophy and sovereignty law.