Posadniks appear together with the state and cities in ancient Russia, their main purpose was to conduct such a policy in the city entrusted to them, which would exactly correspond to the interests of the Grand Duke, as well as the city aristocracy.
The need for management functions
The Old Russian state was born in the ninth century, as a result of successful and energetic actions of Novgorod prince Oleg , a single state emerged - Kievan Rus. The territory of the state was expanding, and there was a need for special people who would represent the prince in the cities of the country. Since the end of the ninth century, Novgorod has played a special role in Old Russian possessions, at one time even acting as a rival to Kiev in terms of primacy in Russia. Unlike other urban settlements, he did not become the inheritance of any princely family, but retained independence and stood apart from all the possessions of the great Kiev prince. In order to control the city, the Kiev rulers sent their sons there, but this was not always the case, not one of the princely grandchildren could gain a foothold there, and the posadnik administration and the popular council received the greatest strength there. It was in Novgorod and Pskov that these people enjoyed the greatest power and could even openly confront the Grand Duke. Thus, the posadniks are, in modern terms, the mayors of the cities of Ancient Russia.

Features of the old Russian control system
Why precisely in Novgorod the posadors possessed such power. There are several reasons for this. The first is that the city originally emerged as a trade and craft center, and this was due to its natural and geographical location. Huge forest lands provided many goods in demand, the abundance of river routes made trade a very profitable business, and, among other things, Novgorod, from the moment of calling the Vikings and the Swedish-German crusaders, did not experience any major external dangers, therefore the power of the princes, who acted as military leaders and supreme judges, was not a special necessity for Novgorodians. Therefore, quite early in the Novgorod posadnik began to be elected from the local population, of course, from the most prosperous part of it at the national assembly - the veche. The interests of major boyars were in the first place here, and in the event of pressure from Kiev, all Novgorodians acted as a consolidated front. Identical orders took shape in other important centers of Novgorod land.

Etymology of the term
In general, the term itself appeared at the end of the tenth century and is found in The Tale of Bygone Years. The first Kiev princes sent their representatives to cities of special importance, and the word itself came from the verb "plant". Sometimes the term "planters" is found, that is, "planters", this is a distorted word that emphasizes the subordination of this person to a certain prince. For example, a planter Yaropolkov - this refers to the head of the city, appointed by the great Kiev prince Yaropolk Svyatoslavovich. If at the initial stage of the existence of Kievan Rus grand-princely leaders were specially sent to Novgorod, later the sons of Russian rulers also played the role of posadniks. But this was characteristically emphasized in the city on Volkhov, it was also called a posadnik, although he was a prince by origin, and throughout the whole feudal fragmentation the city always showed its special status, and the Kiev rulers were forced to reckon with this.

Autonomy of the north-west of Russia and its liquidation
During the period of feudal fragmentation, Novgorod became even more isolated, and from that period, with the exception of Alexander Nevsky’s invitation to repel the German-Swedish invasion, Novgorod posadniks were exclusively local nobles. The leading cities in Russia were changing, from Kiev to Vladimir, from Vladimir to Moscow, but Novgorod continued to maintain its rather broad autonomy, and even the invasion of the Mongol-Tatars could not radically change this tradition. In the fifteenth century, instead of one posadnik, six were elected, each of whom was in charge of certain areas of the city economy, as well as the main posadnik, who was responsible for the coordination and work of all subordinates, in fact, speaking the modern language, it was a city hall with all the attendant powers. Everything changes with the gradual rise of the Principality of Moscow, the unification policy pursued by its princes could not get around this outpost of medieval liberty. By the end of this century, the liberty of Novgorod was crushed by Ivan III, who did not want to have a self-governing unit in his state, the last posadnik Martha Boretskaya was taken to Moscow together with the veche bell, and from this period the post of secession was abolished.
New historical realities
As for the rest of the cities, there the posadniks were appointed by the central authority and did not possess any significant autonomy in the conduct of business. The posadnik’s obligations were not very great, in particular, these included, first of all, the proper provision of tax revenues, trial and reprisals against the local population, law and order in the territory assigned to them, protection of the city and its improvement. That's who such a posadnik in Ancient Russia. However, it is worth noting that the use of this term is most applicable specifically to Novgorod and its lands, in particular Pskov. With the strengthening of central authority, this post was abolished throughout Russia, it was replaced by governors and governors.