What did nobles do in the medieval times? what was there job? plzz ! 29 pts

In the medieval times, there was a system called feudalism present. This was basically a pyramid scheme. The king was at the top, followed by the nobles, then the knights, and finally the peasants. The king would give away land in return for goods. This land also provides the people a sense of security. The king divides land and gives it to the nobles, the nobles divide up their land and give it to the knights, the knights divide up their lands and give it to peasants. The peasants will do work on this land, providing goods/services to the knights, who then give some away to the nobles, who give some away to the king.