Due to the multiple meanings of the term diplomacy, it is presented in the specialized literature either as a science or as an art. As a science, diplomacy has as its object the study of political-legal relations between states, as well as the interests that generate them. As an art, this term indicates the way in which international affairs are administered and implies the ability to order and lead political negotiations. This work approaches the diplomatic field through the prism of science, more precisely the legal one. In the structure of the work, the author highlights in the first part, with historical and political arguments, the formation of the concept of state, deepening and detailing in the work the legal significance of this concept, arguing the place and role that it has in the current paradigm of the world order, as the main subject of Public International Law. The author analyses in detail the organization and functioning of the mechanism that promotes the application of the principles and the achievement of the norms and rules of Public International Law as a whole and which represents the essence of Diplomatic Law. The content of the work is rich in relevant information on the establishment and z:evelopment of relations between states, between states and international ormaizations. thus highlighting that Diplomatic Law serves the general purpose of the international community and does not have as its objective the subjective promotion of the foreign policy of a state or other subject of international law.