The support system between serfs and lords in medieval Europe was known as feudalism. This social and economic system was characterized by a hierarchy where lords granted land to vassals in exchange for military service and protection. Serfs, who were bound to the land, worked for the lords and provided agricultural output. In return, lords offered protection, land tenure, and governance. This relationship created a structured society, with mutual obligations that defined the medieval social order, influencing economic activities and the distribution of power throughout the era.