By International Relations and International Studies we mean the doctrine that comprises the study of foreign objectives and the questions of the political, economic, legal and diplomatic International System subject matters, or rather, plays a role for States, international organisations, non-governmental organisations (NGO), and multinational corporations. In the opinion of Rafael Calduch Cervera, head of the International Relations department (Faculty of media Studies) at the University Complutense of Madrid, it deals with all of those social relations, and the actors that create them, who possess the quality of internationality by contributing in an efficient and relevant manner to the formation, dynamics and disappearance of an international society considered to be a differentiated society.” Consequently, the term ‘international relations’ must be applied both to the subject being studied as well as the academic discipline; that’s why in the Spanish language a name is written in small letters when referring to the combination of already known relations, whereas the term with capital letters – International Relations – refers to the academic body. Although its genesis was historical-political, today the expression fundamentally takes in economic, cultural and sociological elements. For many, International Relations become a branch of Political science, a way of highlighting this discipline as a field of interdisciplinary, multidisciplinary and trans-disciplinary studies. Known since the times of Thucydides (Greek historian and soldier born in Athens 460 BC and died around 395 BC) the formal studies that gave way to the creation of a University degree in International Relations, and consequently, into a definite subject matter, which happened only during the last century. The horizon for International Relations is wide-open, with the analysis and formulation of States’ foreign policies standing out. Likewise, there are other subjects like Economy, International Politics (debut and development of which took place during the 1970s), International law, Philosophy, geography (through Geopolitics), Sociology, Anthropology and Psychology, to name only the most recurrent. These days, the most reviewed themes in International relations are globalization, the State, ecology and sustainable development, terrorism and organized crime, disarmament and arms control, nationalism, economic development, international finances and the rights of Man, among others.