International relations (IR) or international affairs, depending on academic institution, is either a field of political science or an interdisciplinary academic field similar to global studies, in which students take a variety of internationally focused courses in social science and humanities disciplines. In both cases, the field studies relationships among countries, the roles of sovereign states, inter-governmental organizations (IGOs), international non-governmental organizations (INs), non-governmental organizations (NGOs), and multinational corporations (MNCs). International relations is an academic and a public policy field, and so can be positive and normative, because it analyzes and formulates the foreign policy of a given State.As political activity, international relations dates from the time of the Greek historian Thucydides (c. 460–395 BC), and, in the early 20th century, became a discrete academic field (No. 5901 in the 4-digit UNESCO Nomenclature) within political science. In practice International Relations and International Affairs forms a separate academic program or field from Political Science, and the courses taught therein are highly interdisciplinary.For example, international relations draws from the fields of: technology and engineering, economics, history, and international law, philosophy, geography, social work, sociology, anthropology, criminology, psychology, gender studies, cultural studies, culturology, diplomacy. The scope of international relations comprehends globalization, diplomatic relations, state sovereignty, international security, ecological sustainability, nuclear proliferation, nationalism, economic development, global finance, as well as terrorism and organized crime, human security, foreign interventionism, and human rights, as well, as, more recently, comparative religion.