Feudalism: A social system in medieval Europe where peasants worked land owned by nobles in exchange for protection.
Serfdom: The status of many peasants under feudalism, similar to slavery. Serfs were bound to the land and could not leave without their lord's permission.
Guilds: Associations of artisans or merchants who control the practice of their craft in a particular town. They often set standards for quality, prices, and working conditions.