Knights would protect their king overall. Knight had a pretty good life. They had a good amount of money. Also they would get the armor and weapons they needed for free. Knights would have to train for many years.
Lords, and noblemen had great lives. They were rich, and had their own lands called manors. They were very high on the pyramid. Lords had serfs and peasants, and sometimes they would respect them, and not the king.
Kings and Queens had the best life then. They were extremely rich, and people would respect them. They would get their own land, and they would give land to the best lords and noblemen. They were at the top of the pyramid.
This was feudalism. It helped keep medieval Europe stable for a while. It may not be fair, but I guess it worked for them. As you go down the pyramid of feudalism there are more people in that class.
Feudalism was a good thing and a bad thing. It was good because it keep people from attacking, and everyone knew there part. It was bad because it caused problems, and it wasn't fair for people.