This book investigates the intersection of terrorism, digital technologies and cyberspace. The evolving field of cyber-terrorism research is dominated by single-perspective, technological, political, or sociological texts. In contrast, Terrorism Online uses a multi-disciplinary framework to provide a broader introduction to debates and developments that have largely been conducted in isolation. Drawing together key academics from a range of disciplinary fields, including Computer Science, Engineering, Social Psychology, International Relations, Law and Politics, the volume focuses on three broad themes: 1) how - and why - do terrorists engage with the Internet, digital technologies and cyberspace?; 2) what threat do these various activities pose, and to whom?; 3) how might these activities be prevented, deterred or addressed? Exploring these themes, the book engages with a range of contemporary case studies and different forms of terrorism: from lone-actor terrorists and protest activities associated with 'hacktivist' groups to state-based terrorism. Through the book's engagement with questions of law, politics, technology and beyond, the volume offers a holistic approach to cyberterrorism which provides a unique and invaluable contribution to this subject matter. This book will be of great interest to students of cybersecurity, security studies, terrorism and International Relations.