The dominant political system in medieval Europe was feudalism. This hierarchical system was characterized by the exchange of land for military service and loyalty. At the top of the feudal hierarchy was the king, followed by powerful nobles or lords who held large estates. Vassals, or knights, served these lords and were granted smaller portions of land known as fiefs. At the bottom were serfs or peasants, who worked the land and provided agricultural produce. Feudalism shaped social structure, governance, and economic practices during the Middle Ages, driving local economies and influencing relationships between different social classes.