Even though neutrality, the non-participation of states in international armed conflicts, is a well-known concept of traditional international public law, its value in the 21st century is disputed. Some regard the concept as obsolete while others still view it as an important contribution to a peaceful world. This book analyses the contemporary international law concept of neutrality. At the heart lies the question of the present-day value of neutrality for international law. For the deeper understanding of the international law concept of neutrality, a historical overview of neutrality is followed by a presentation of the different types of neutrality as well as the remaining neutral states of the 21st century. The study of the sources of neutrality law, its scope of application as well as the detailed rights and duties of neutral states will answer the question of what it entails nowadays to be neutral in the legal sense. Important is therefore also a clear distinction between the law and politics of neutrality. Special attention is given to the traditional problem of the export of war material as well as to the newer occurrences of private military and security companies and cyber warfare. The focus of this book lies on Switzerland as the archetype of a contemporary neutral state.