Who were the users of a land ownership system known as feudalism?

Feudalism was a system of land ownership and social hierarchy that became prominent in England after the Norman Conquest in 1066. Think of it like a pyramid: at the top was the King, who owned all the land. He then granted portions of this land to his loyal supporters, the Barons, in exchange for military service and loyalty. These Barons, in turn, subdivided their land to Knights, who also pledged military service. At the bottom were the peasants or serfs, who worked the land and provided services to the Knights in exchange for protection. While elements of a similar system existed before, it was the Normans who formalized and implemented feudalism on a large scale in England to consolidate their power and control after conquering the Anglo-Saxons. So, while the Anglo-Saxons, Romans, and Vikings all had their own systems of social organization, it was the Normans who are most associated with the formal establishment and widespread use of feudalism in England.