There's variations on duke. Now, the duke might have his own manner or might even have multiple manners that he rules directly over, that has his own serfs or free peasants working that land, providing output, which helps generate some of the tax revenue that goes to the king or provides some of the necessities for the duke's own household. But the rest of the duchy, they might subdivide further and they would be lord over their own vassals. So, for example, this piece of land right over here, this duke might provide it to someone else, let's say a count, in which case this would be called a county, and that is where we get our modern term, county, and this count would be vassal to the duke, and the duke would be the lord of the count, and then the count can then be the lord of someone else, of their vassals, and this goes on and on and on all the way until you get down to the level of the serfs and the peasants who are actually doing the work. But the main idea here is is that in exchange for land, the king gave this duke a duchy, or maybe the king's father gave this duke's father this duchy, and so this grant of land, this is called a fief, a critical term in the feudal system. This county here, this is a fief. In exchange for that, the vassal gives the lord resources, taxes, and loyalty.