Most communities in the Ninth World have a strict class structure. Although there are exceptions (such as in Lostrei), in most places there is an aristocracy, a middle class, a low class, and a slave class. The details can vary, as can how one’s class is determined. Most of the time, however, the class into which you are born is the class in which you will remain for your entire life.
Thus, the aristocracy are born to their station and have greater wealth and greater access to food, health care, and other resources than anyone else. They also have authority over those beneath them. Sadly, it is the rare aristocrat who does not abuse these advantages. Nobles are aristocrats with titles, such as baron, duchess, and so on.
The middle and low classes are usually different only in the amount of wealth they possess. Middle-class residents of cities and towns often have their own house, for example, while the lower classes live in communal buildings or on the street. These classes have varying rights, but in the end they are almost always subject to the aristocracy. It is possible for a middle-class individual to be wealthy or even extremely wealthy, but not technically an aristocrat. This, however, is rare, in that the class system is constructed to keep non-nobles from accumulating much wealth and because in some places, it is possible to buy one’s way into the upper class.
Slaves are those captured in war or, more commonly, the children of slaves. They can also be members of the lower class that have accumulated high debt and no way to pay. Last, sometimes criminals are sentenced to be slaves. Slaves have few rights and can be bought and sold. In some communities, slavery is limited—you might be a slave until you have worked off your debt—but most of the time, it is a permanent status. In a few places, slaves have absolutely no rights and can be killed without repercussion.