Feudalism was a social system in which ownership of land was granted by a lord to an individual in exchange for his military service. The unit of land given in the agreement was called a fief.
Rulers or lords provided land and protection to those who agreed upon military service in the regions they controlled. The individuals under the jurisdiction of the lords were known as vassals, and commonly they referred to those who gave them land as their lord or liege. It was common for vassals to serve a yearly amount of 40 days of military service, although the exact amount of time necessary to honor the agreement varied with each lord and vassal. The vassal's talent and the lord's financial stability potentially affected the agreement, and it often led to the exchange of money rather than land to purchase a vassal's loyalty and services if needed.
Feudalism encouraged the creation of individual land ownership, creating a type of military hierarchy that discouraged the idea of a unified government. Vassals could divide their lands into smaller sections and offer them to individuals of lower status, who would often repeat the process to profit off the land. This led to the stifling of economic expansion, as vassals and those who worked the lord's land were typically discouraged from trading with other regions, while the goods they produced were heavily taxed by their liege as additional payment for their land ownership.