This document provides an overview of key theories in international relations, including realism, liberalism, Marxism, and constructivism. It discusses the main assumptions and policy prescriptions of each theory. Realism focuses on state power and security, seeing states as rational actors. Liberalism emphasizes international cooperation and institutions. Marxism views the international system as perpetuating capitalist exploitation. Constructivism examines how state identities and non-state actors shape international politics. The document aims to describe, explain, and predict international relations from the perspectives of different theoretical approaches.