How did the feudalism system protect a lord as well as his peasants

Feudalism is basically when the lord(king) grants fief(land) to the peasants or knights in exchange for protecting the lord. The feudal System protected the lord as well as the peasant by giving everybody what they want. By giving the peasants land, they are less likely to rebel and more likely to listen to the king(and protect him) this way both the king and the peasant are benefiting.

Hope this helped :)