Generally people's "class" is defined by how much money they make. In the U.S. generally there are three classes: poor, middle class, and rich. Some people also think there is another class in between poor and middle class called working class. United States culture is based on the idea that people can move up the economic ladder and become middle class or even rich if they were born poor. This is the idea of going from "rags to riches". Moving up the class ladder is not easy though. Higher education needed to get a good paying job is expensive.