In international relations, power is defined in several different ways. Material definitions of state power emphasize economic and military power. Other definitions of power emphasize the ability to structure and constitute the nature of social relations between actors. Power is an attribute of particular actors in their interactions, as well as a social process that constitutes the social identities and capacities of actors.
International relations scholars use the term polarity to describe the distribution of power in the international system. Unipolarity refers to an international system characterized by one hegemon (e.g. the United States in the post–Cold War era), bipolarity to an order with two great powers or blocs of states (e.g. the Cold War), and multipolarity refers to the presence of three or more great powers. Those states that have significant amounts of power within the international system are referred to as small powers, middle powers, regional powers, great powers, superpowers, or hegemons, although there is no commonly accepted standard for what defines a powerful state.
