Because security is a fundamental concern for individuals, societies, and states, this course provides a systematic introduction to how International Relations (IR) and Security Studies define, analyze, and debate “security.” War and conflict recur throughout human history for instance, but why do they occur, under what conditions do they escalate, and what patterns shape how actors anticipate, deter, or fight? Drawing on major theoretical traditions as well as historical and contemporary cases, the course introduces core concepts and terminology such as power, deterrence, the security dilemma, alliances, coercion, and escalation and shows how they are applied to real-world security problems. By the end of the course, students will be able to evaluate competing explanations of conflict and assess the policy trade-offs involved in managing threats in international politics.