The discipline that studies interactions between and among states, and more broadly, the workings of the international system as a whole. It can be conceived of either as a multidisciplinary field, gathering together the international aspects of politics, economics, history, law, and sociology, or as a meta‐discipline, focusing on the systemic structures and patterns of interaction of the human species taken as a whole. The discipline acquired its own identity after the First World War. Its principal branches additional to theory include international political economy, international organization, foreign policy‐making, strategic (or security) studies, and, more arguably, peace research. If area studies is added to these, the label international studies becomes more appropriate. When spelled wholly in lower case, the term refers to the totality of interactions within the international system. The emphasis is often on relations between states, though other collective actors such as multinational corporations, transnational interest groups, and international organizations also play an important role.