The study of international relations (IR) focuses on the interactions and behaviors of states, as well as how those actions affect the world as a whole. IR scholars examine a range of issues, including the causes and effects of war and peace, economic development, political instability and terrorism. The field is interdisciplinary, and it draws on theories and ideas from a number of other fields, such as anthropology, history, law, philosophy, and political science.

The belief that a group of people should be considered a sovereign nation with a right to control its own affairs, and that other nations are bound by its own laws and should respect its borders. Sovereignty is also a principle that guides the creation and maintenance of international organizations such as the United Nations and NATO.

A group of countries or an international organization that enters into a formal agreement to pursue shared interests, usually military ones. Alliances can be open and indefinite, such as NATO or APEC, or they can be entered into for specific purposes, such as the coalitions of the willing that fought the Iraq war in 2003.

A state dissatisfied with the current global order and that wants to revise it, like Russia or China. Changing the status quo can have dramatic consequences, as was seen in the overthrow of governments in France, Russia and Iran. This kind of revolution may reshape domestic politics, as it did in those countries, but it can also influence regional or even global politics — see Arab Spring.