A basic understanding of the concept of security can be defined as; protect your interests from external threats. This concept of security in the context of everyday use seems like a rather simplistic idea given the basic definition. However, a deeper examination of the concept of security reveals the true complexity surrounding the nature of security and what it attempts to encompass, especially when the term "security", used in an everyday context, can be seen as such a broad topic. Baldwin (1997) points out that the identification and analysis of shared elements of security leads to further discussion of such elements from various approaches. These approaches presuppose certain worldviews that can help understand the concept of security from different perspectives. This essay will try to define the concept of security from the perspective of a realist approach; Because political realism has been so central to international politics, there is much to draw from its conception of security. Although the realist concept of security has explained and influenced how security in the international system has functioned historically, it fails to predict security problems caused by non-state actors and transnational organizations, as well as other factors of international relations. Political realism makes key assumptions about the international system and how nation states operate; these assumptions therefore have implications for the way in which the concept of security is interpreted in the international system. These assumptions, as argued by realist theorists such as Morgenthau (1993) and Mearsheimer (2001), are this; the international system is anarchic, meaning that there is no authority above nation states that can enforce laws or protect states; ...... half of the paper ...... agenda for international security studies in the post-Cold War era (pp. 1-34). Boulder: Lynne Rienner Publishers.Donnelly, J. (2005). Realism. In AL-S. Scott Burchill, Theories of International Relations (3rd ed., pp. 29-54). New York: Palgrave MacMillan.Glaser, C. L. (1994/95). Realists as well as optimists. International Security, 19(3), 50-90.Glaser, C. L. (2007). Realism. In A. Collins, Contemporary Security Studies (pp. 15-33). Oxford: Oxford University Press. Mearsheimer, J. J. (1994/95). The false promise of international institutions. International Security, 19(3), 5-49. Mearsheimer, J. J. (2001). The tragedy of great power politics. New York: Norton.Morgenthau, H. J. (1993). Politics Among Nations: The Struggle for Power and Peace (Rev ed.). New York: McGraw Hill. Waltz, K. N. (1979). Theory of International Politics (1st ed.). New York: McGraw-Hill.