The only real source of wealth in the Middle Ages were land, each plot was called a fief. Those aristocrats might then give smaller fiefs to lesser nobles. Then the peasants who lived on the land worked for someone called a lord, which is a land owner. Then peasants would get to be allowed to live on the lord's land The lord would also provide crops and military service to the person that gave him his fief. This is called feudalism, where devotion and taxes are exchanged for land. Now, today the “lord of the land” is simply called the land lord, and the peasants are called housekeepers or maids.
What is the definition of feudalism?
Feudalism is a system of government in which land is exchanged for devotion and taxes, and in which a lord provides crops and military service to the person who gave him his fief.