People lived in castles during medieval times under a feudal system established by William the Conqueror. Lords owned the land and gave some to knights in exchange for military service. Peasants or serfs farmed the land or worked as craftsmen. The castle housed the lord and his family, knights and their families, and many servants who fulfilled roles like cooking, cleaning, crafting, and providing security. Life in a medieval castle involved hierarchies and specialized jobs that supported those who lived and worked there.