This is an accessible new examination of what 'security' means today, contextualizing the term amongst other key ideas, such as the nation state, diplomacy, war and autonomy. By exploring the many differing conceptions of security, this study clearly explains how the idea of security in world affairs can be understood in relation to other ideas and points of view. It shows how, when standing alone, the word 'security' is meaningless, or just an empty term, when divorced from other ideas distinctive to international life. This essential new volume tackles the key questions in the debate: what norms of sovereignty relate to security? does security necessarily follow from the recognition of identity? what sort of obligations in respect of security attach to power? how far can a political arrangement of empire remedy human insecurity? can trusteeship provide security in a world of legally equal sovereign states? is security the guarantor of freedom? This book is an excellent resource for students and scholars of security studies and politics and international relations.