In diplomatic history, the term “Interwar Period” refers to the specific period between 1918 and 1939. The early years of interwar period was relatively peaceful and optimistic, yet especially the term after 1929 was characterized by insecurity. The Great Depression, Italian invasion of Abyssinia, Japanese invasion of Manchuria, German invasion of Czechoslovakia and inefficient structure of the League of Nations to react these crises were the major themes in the diplomatic agenda of this term.

This is a type of international system in which one hegemon significantly dominates the other actors within the system. A typical example of such an international system is the period of early 1990s. The United States remained as the only superpower after the dissolution of the Soviet Union and dominated the international system.

In bipolar international system, there are two major powers that are significantly superior to other actors in terms of distribution of power. A perfect example of
such an international system is the Cold War term in which the United States and Soviet Union appeared as the two superpowers.

Multipolarity refers to an international system with at least three great powers of which are similarly distributed. The period before the Great War (First World War) can be considered a multipolar international system. It can be argued that the military capacities were almost equally distributed among at least four actors, namely Britain,
France, Germany and the United States before the Great War.

The term “Old World” here refers to a period of time starting from ancient world to emergence of Renaissance especially in Italian peninsula. The political authorities of the “Old World” were far from being as organized as modern state structures.

The main difference between ancient states and modern state structures was lying in the capacity of centralization. The ancient states in the “Old World” were mainly constituted of some local authorities which control a piece of land militarily and economically. These local authorities were brought together under more general state
structures borders of which reach out broader territories.

Pacta sunt servanda is a legal term in Latin, which refers to the continuity of agreements between parties and bindingness of the clauses for both parties regardless
of a change of a government or ruler. It is one of the ordering principles of modern
international law and diplomacy.

The signals of the resident ambassadors, considered as an element of modern permanent diplomacy, were first detected in the diplomatic practices of medieval world in the form of a nuncius. The clear signals of transition to permanent institutions and professional diplomats were, however, seen mainly in the Italian city states during the Renaissance.

Italian peninsula was home to certain developments that impacted the whole European
political context especially in the 15th and 16th centuries. Began in Florence in the 14th century, the period called Renaissance contributed to the developments not only in art, philosophy and science, but also in the conduct of diplomacy.

Firstly, the political equation among small Italian city states facilitated the consolidation of diplomacy as a preferred tool for solution of the problems in the Peninsula. Italian city states were in fact feudal units controlled by certain dynasties. In other words, each city state was actually the piece of land that was held by a certain noble aristocrat family. In this regard, the institutionalization of equality through Peace of Lodi accelerated the emergence of diplomatic customs as a legitimate practice in Italian Peninsula. Secondly, the common language that is shared by all these small city states served as another facilitator for diplomatic progress in the region. Despite the lack of a political unity among the city states, there was a linguistic unity among them.of correspondence among the city states. This became an asset for the facilitation of dialogue and prepared the ground for diplomatic interactions to become an effective tool in the interstate affairs. Thirdly, the small scale political organization due to over-fragmented political structure in the Peninsula rendered some other coercive political tools such as war much more costly and ineffective. Therefore, a common willingness and consensus emerged among Italian city states to solve their disputes through diplomatic interactions instead of military methods. All these things combined paved the way for institutionalization of diplomacy in a much deeper and organized manner in Italian Peninsula compared to elsewhere in Europe. 

Baiulo of that was sent to Constantinople by Venetians should be considered as the first resident ambassador that was sent outsideof the Italian city states context. He was certainly a permanent representative of Venetia who acted in a quite similar manner to a modern consul.

Major difference between modern ambassadors and resident ambassadors of the Renaissance was that usually the resident ambassadors of Renaissance were sent to
a country for a lifetime, whereas modern diplomats are rather appointed for a limited time and could be appointed several times to different countries. This lifetime appointment of the resident ambassadors in Renaissance also caused certain problems such as losing the contact with the home country after quite some time in the host country. The resident ambassadors sometimes internalized the country of appointment after a significant time of stay, and this caused weakening of the ties with the home country in some cases.

The Peace of Westphalia is signed in 1648 after 30 Years’ Wars between protestant
and catholic German principalities. There is a consensus that the Peace of Westphalia
introduced the modern notion of sovereignty to interstate relations, therefore, is accepted as the beginning of the modern state system. It established the functional
equality among German principalities regardless of their religious/sectarian orientation, size and power.

Although France did have envoys and resident diplomatic missions in several countries as early as the beginnings of 16th century, it did not follow the general European fashion to build resident and constant diplomatic missions in European capitals. 

Firstly, diplomatic immunity was recognized by all parties in Europe as a general principle of diplomacy. In this regard, immunity was guaranteed multilaterally to assure the credibility and authenticity of the information delivered by the envoys.  Secondly,
arrival of a new diplomatic mission to a capital started to be welcomed ceremonially by the host country. 

Diplomatic immunity is a universal principle of modern diplomacy which refers to legal immunity of diplomats and diplomatic missions. According to diplomatic immunity principle, diplomats are not susceptible to lawsuits and diplomatic missions such that embassies are immune from the intervention of the host country. Diplomatic immunity has been an important custom in the transition to permanent diplomacy.

Napoleon appeared as the distributer of two very dangerous ideologies throughout the Europe: republicanism and nationalism. The former is dangerous because it poses a challenge to the very idea of monarchy, in fact, it is the anti-thesis of monarchy. The latter is dangerous because almost all European monarchies were relying on multi-national empires and the nationalist ideology would mean the dissolution of these multi-national empires, which later caused so.

Firstly, they allocated generous budgets for the accommodation and expenses of the diplomatic missions sent to other countries. Secondly, expansion of the diplomatic missions also required a deeper and better planned training curriculum, which was developed later and included modules varying from general rules of manners to diplomatic correspondence techniques. Besides, language courses were also provided to newly appointed diplomatic staff.Thirdly, as different from the 18th century resident ambassadors, the ambassadors of permanent diplomacy in the 19th century were not
only seen as the envoys of their ruler. They were also authorized to develop instant policies as a reaction to sudden developments and crisis situations.

This is a French term that refers to the corrupted traditional monarchy in France
before the French Revolution.

Firstly, the nature of foreign policy shifted from a pure state-centric to a more multiactor and multi-factorial ground.Secondly, states also noted the changes in the
nature of the diplomacy and they also developed new strategies to address the new necessities of international politics.