What was the basis for the division of medieval society?

It was based on feudal relations. So was the lord who owned the land, and the peasants worked on this land. They were forced to work for the lord and pay taxes to him. On the other hand, there was a feudal hierarchy, which was a feudal ladder, where feudal lords of different levels were located. So one feudal lord was a subordinate of another feudal lord, that is, he was a vassal. Each vassal had to faithfully serve his liege, for which he awarded him with land.