Power in international relations is defined in several different ways. Political scientists, historians, and practitioners of international relations (diplomats) have used the following concepts of political power:

• Power as a goal of states or leaders;
• Power as a measure of influence or control over outcomes, events, actors and issues;
• Power as reflecting victory in conflict and the attainment of security; and,
• Power as control over resources and capabilities.

Modern discourse generally speaks in terms of state power, indicating both economic and military power. Those states that have significant amounts of power within the international system are referred to as middle powers, regional powers, great powers, superpowers, or hyperpowers, although there is no commonly accepted standard for what defines a powerful state.

Entities other than states can also acquire and wield power in international relations. Such entities can include multilateral international organizations, military alliance organizations (e.g. NATO), multinational corporations, non-governmental organizations, or other institutions such as the Roman Catholic Church or the Hanseatic League.