Cyber security is concerned with the identification, avoidance, management and mitigation of risk in, or from, cyber space. The risk concerns harm and damage that might occur as the result of everything from individual carelessness, to organised criminality, to industrial and national security espionage and, at the extreme end of the scale, to disabling attacks against a country’s critical national infrastructure. However, there is much more to cyber space than vulnerability, risk, and threat. Cyber space security is an issue of strategy, both commercial and technological, and whose breadth spans the international, regional, national, and personal. It is a matter of hazard and vulnerability, as much as an opportunity for social, economic and cultural growth. Consistent with this outlook, The Oxford Handbook of Cyber Security takes a comprehensive and rounded approach to the still evolving topic of cyber security. The structure of the Handbook is intended to demonstrate how the scope of cyber security is beyond threat, vulnerability, and conflict and how it manifests on many levels of human interaction. An understanding of cyber security requires us to think not just in terms of policy and strategy, but also in terms of technology, economy, sociology, criminology, trade, and morality. Accordingly, contributors to the Handbook include experts in cyber security from around the world, offering a wide range of perspectives: former government officials, private sector executives, technologists, political scientists, strategists, lawyers, criminologists, ethicists, security consultants, and policy analysts.