This chapter examines the impact of cyberpower on the conduct of war and what it means for the future of strategy and conflict. Cyberspace is a globally connected domain created by the rapid spread of information-communication technologies around the world. As a result, various actors, from individuals and small groups to non-state actors and governments, are now capable of launching cyber-attacks that present enormous challenges for strategists. The chapter first provides an overview of terms and definitions relating to cyberspace, cyberpower, and cyberwar before discussing the characteristics and attributes of cyberspace, cyberpower, and the infosphere. It then explains how cyberspace has emerged as a place of constant conflict, focusing on the problem of cyber security as well as the challenges and unknowns of cyber-attack. It concludes with an analysis of how cyberpower may trigger a twenty-first-century revolution in military affairs by reshaping international politics and altering the character of war.