The international political system is a complex, dynamic process. The study of this system involves a wide range of issues at the national, bilateral, multilateral and regional levels. In broad terms, international politics is the pattern of power relationships that determines the conduct of states and their impact on world affairs. The study of international politics includes the study of history, geography and economics.
The political process that enables a group of sovereign nations to establish an international system in which each state recognizes its own sovereignty but co-operates with other states on a variety of political, social and economic issues. The development of modern international politics was accelerated by the Protestant Reformation, which undermined the authority of the Catholic Church and promoted nation-states asserting their independence from papal rule. The end of the Cold War triggered a shift towards a unipolar system and now a possible bipolar one, with the United States and China competing to dominate global politics.
Realism is an approach to studying international relations (IR), which assumes that state action in the international arena is largely determined by self-interest and that, therefore, international relations are essentially a zero-sum game of conflict and anarchy. Its main competitor is liberalism, which takes a more optimistic view, arguing that a wide array of institutions and actors, including individuals, private parties, multinational corporations and the United Nations, have mediating powers that promote cooperation and peace. In addition, it stresses that, although states are sovereign and mainly act in their own self-interest, they should pursue ethical and moral goals such as promoting democracy and human rights.