This Handbook brings together 30 state-of-the-art essays covering the essential aspects of global security research and practice for the 21st century. Embraces a broad definition of security that extends beyond the threat of foreign military attack to cover new risks for violence Offers comprehensive coverage framed around key security concepts, risks, policy tools, and global security actors Discusses pressing contemporary issues including terrorism, disarmament, genocide, sustainability, international peacekeeping, state-building, natural disasters, energy and food security, climate change, and cyber warfare Includes insightful and accessible contributions from around the world aimed at a broad base of scholars, students, practitioners, and policymakers