This chapter provides an introduction to international politics. It gives a history of the international system and examines the possibilities in the aftermath of the Cold War. It then contrasts politics among states with politics within states, noting the major features of international politics such as the lack of a central authority, communication difficulties between states and the more neutral moral tone of global politics. It explores the sources of power in international politics and the various ways leaders of states and international organizations make collective choices. The nature of international power is reviewed. The chapter ends with an examination of ethnic conflict in Rwanda as an example of a failure of international actors, and an overview of the history, functions, and challenges faced by the United Nations.