China's emergence as a major global power is reshaping the cyber domain. The country has the world's largest internet-user community, a growing economic footprint and increasingly capable military and intelligence services. Harnessing these assets, it is pursuing a patient, assertive foreign policy that seeks to determine how information and communications technologies are governed and deployed. This policy is likely to have significant normative impact, with potentially adverse implications for a global order that has been shaped by Western liberal democracies. And, even as China goes out into the world, there are signs that new technologies are becoming powerful tools for domestic social control and the suppression of dissent abroad. Western policymakers are struggling to meet this challenge. While there is much potential for good in a self-confident China that is willing to invest in the global commons, there is no guarantee that the country's growth and modernisation will lead inexorably to democratic political reform. This Adelphi book examines the political, historical and cultural development of China's cyber power, in light of its evolving internet, intelligence structures, military capabilities and approach to global governance. As China attempts to gain the economic benefits that come with global connectivity while excluding information seen as a threat to stability, the West will be forced to adjust to a world in which its technological edge is fast eroding and can no longer be taken for granted.