Final answer:
The serf was the social class at the bottom of Medieval Society. They were unfree laborers who worked the lands of the nobles, under harsh conditions with few rights, and they could not leave the manor without permission.
Step-by-step explanation:
The social class that was at the bottom of Medieval Society was the serf. In the feudal system that defined the Middle Ages, serfs were considered the lowest rank within the social hierarchy. These unfree laborers were tied to the land, working the fields of their lords, and were not allowed to leave the manor without permission. They had very few rights and owed a great deal of service to the nobility. They were differentiated from slaves in that they could not be bought or sold, but their existence was one of subsistence and hardship, hardly better than that of the enslaved.
Merchants and artisans made up other classes within medieval towns, and although they were non-elite, they held more freedom and potential for economic advancement compared to serfs. The nobles, knights, and clergy formed the upper echelons of medieval society, with the king often at the top. However, over time, as events like the Black Death and the Hundred Years' War unfolded, the rigid feudal system began to weaken, allowing other classes, such as the merchants, to rise in power and influence.