Diplomatic law has evolved throughout human history. From time to time, diplomatic law has changed, i.e. adapted to the way in which this right is understood in governing structures. In the past, diplomatic law was most often regulated by the states themselves, which means that they determined the rights and obligations of diplomats themselves. Recent times have been marked by international documents prescribing the rights and obligations of diplomats and other stakeholders in international law. The key document is the Vienna Convention. It regulates all key issues related to diplomacy, diplomatic relations, diplomatic immunity. The aim of this paper is to present changes in diplomatic relations throughout history and fundamental features of modern diplomacy and diplomatic relations, ie modern diplomatic law. The paper pointed out that modern diplomatic law is the legal basis for the realization of diplomatic relations in Western countries and that the rights and obligations of all stakeholders in diplomatic law are based on this law. An example from practice showed how diplomatic relations, in addition to general documents, are based on numerous agreements that countries sign with each other.