The poor, the middle class, and the rich all have different ways which their cash flows. The poor and middle class are really of the same class; they are, for simplicity's sake, poor. However, because there are some minor differences, we will look at them individually. Let's take a look at the poor first.
The poor have an income, but it is usually small. They work hard, and they earn money; sometimes, this money is a considerable amount. However, they spend their money very unwisely. They spend it all, or at least most of it. This leads to them being poor and never getting ahead. They have no discipline at all with their money. They do not save, and they pay for it dearly by being poor; however, they are often ignorant to this process.