All you have to do is summarize easy
the backbone of medieval society was a system of allegiance between lords and vassals, the character of which varied from place to place, but which generally meant a grant of land given by a lord to a vassal in exchange for military service. however, that system of allegiance only refers to the actions within one group of the three main orders of medieval society: those "who fought." there were also those "who prayed," the clergy and monastic organizations, and those "who worked," the peasant farmers who made up the vast majority of the population. these three groups, those who fought, those who prayed, and those who worked, came to be known as the "three orders" (or "three estates"). people looked to the rich and powerful nobles, called lords, for protection. the lords owned large estates and had armies to defend them against attack. free men looking for the lord's protection accepted the lord's offer and become serfs. serfs agreed to farm the lord's land and give him a portion of their crops. this system of working in return for protection was known as feudalism (see image on the right). wars often broke out between the various regional lords who wanted to expand their land holdings and add to their estates. the warriors that fought on behalf of the lords were known as knights. knights were known for their bravery and skill. eventually castles were constructed as the ultimate defense system against the constant wars.