This updated and expanded edition of Cyberspace in Peace and War by Martin C. Libicki presents a comprehensive understanding of cybersecurity, cyberwar, and cyber-terrorism. From basic concepts to advanced principles, Libicki examines the sources and consequences of system compromises, addresses strategic aspects of cyberwar, and defines cybersecurity in the context of military operations while highlighting unique aspects of the digital battleground and strategic uses of cyberwar. This new edition provides updated analysis on cyberespionage, including the enigmatic behavior of Russian actors, making this volume a timely and necessary addition to the cyber-practitioner's library. Cyberspace in Peace and War guides readers through the complexities of cybersecurity and cyberwar and challenges them to understand the topics in new ways. Libicki provides the technical and geopolitical foundations of cyberwar necessary to understand the policies, operations, and strategies required for safeguarding an increasingly online infrastructure.