International politics is the study of the relations between the world’s countries. In practice, it involves the study of conflict and adjustment between nations that acknowledge no common supreme authority. The Western state system has in the last three centuries allowed for gradual fulfillment of aspirations for national independence, but at a great cost of intermittent war — about a dozen major general ones involving most of the leading states. Because of this record the study of international politics has been recognized as important.
The emergence of a world economy has given rise to new forms of international groupings and international political institutions. These range from intergovernmental organizations — such as the League of Nations and its successor, the United Nations — to multilateral trade and economic agreements and regional groupings like ASEAN and Mercosur.
Among the earliest of these were socialist and radical trade unions — including the First, Second and Third Internationals — that attempted to organize workers across national boundaries and achieve international socialism (see world revolution). Later, more liberal conceptions of internationalism advocated free trade and global economic competition as a means to promote peace and mutual interdependence.
Revisionist states, feeling disadvantaged by the international status quo, seek fundamental change in its rules and practices. Whether their aspirations are met or not, many states develop armaments to ensure that they cannot be overwhelmed by more powerful rivals. The result is a balance of power — the pattern of relations among nations — that forms the heart of international politics.