As a theory of international relations, realism has a long and complicated history whose roots can be traced back to the writings of the ancient philosophers of Greece, Rome, and China. However, the use of political realism increased in the twentieth century after Edward Hellet Carr's Twenty Year Crisis came to guide the rest of the schools of thought present in the field of international relations. Others soon joined Carr's views: Schuman (1933), Nicolson (1939), Niebuhr (1940), Schwarzenberger (1941), Wight (1946), Morgenthau (1948), Kennan (1951), Butterfield (1953), and Waltz (1969). Realism emphasizes the fact that states should rely on themselves to ensure their security in the anarchic international system. Hostile security interests and changes in the balance of power will lead to conflicts. As for the term, although it is not certain where its origins lie, most scholars agree that either EH Carr or Hans Morgenthau may have coined it (????). In his analytical study of the Peloponnesian War (431-415 BC), Thucydides presents the ancient Greek war between Athens and Sparta as a consequence of Sparta's fear of the growth of Athens, a city-state that felt the need to ensure their safety through violence. The emphasis is on human nature, which is reflected in the behavioral pattern of the state, but is linked to domestic politics and national wealth. Followers of Thucydides' type of realism, identified as neoclassical realism, base their fear on the idea that the more a state extends, the more its imperialist tendencies will extend, because it will need more resources; and the more resources you have, the more your ambitions will grow. It is something like a vicious circle.Acco...... middle of paper ......The emergence of states as a superpower without opponents in the political, economic and technological arena. However, even US hegemony was unable to avoid conflict in the new post-Cold War world. The realist approach received a new impetus with Waltz's new interpretation of realism. For him, state behavior was the product of competition between states. His book, Labor Theory of International Politics, brought a new debate to fading realism. In the early 1990s, the relist approach lost much of its support, influenced by international events, the most notable of which was the end of the bipolar world. Slowly a new type of realism emerged: neorealism. If we take into account the different phases of the Cold War and the post-Cold War era, we come to the conclusion that realism was, is and will be the dominant theory in the field of international relations.