Feudal farm workers, also known as SERFS (5 letters), were peasants in the Middle Ages who were bound to the land and worked on the farms of their lords. They were not free to leave the land and had to pay rent or labor services to their lords in exchange for the use of the land. SERFS were also expected to provide military service to their lords when needed. They were considered to be part of the lord's estate and were subject to his authority.