As an important aspect of human polity, the concept of security has an important place and space in politics. Though regularly mentioned or referred, the concept is rarely given a proper definition, usually left in the shadows of politics and policymaking and usually referred as a cause to an effect. Within the framework of this book, classic, modern and post-modern security issues are analyzed, while also focusing on the classical and diverse conceptual dimensions of security, current problems are also evaluated, especially in the axis of post-modern security studies. In security studies, a distinction is usually made between classical and post-modern approaches, but in this study, both are considered together. One of the important features of this work is that it offers a perspective from Turkish experts on the concept of security in international relations.