The Lower, Middle, and Upper Classes are basically groups divided by income. The lower class usually earns the least, the upper class earns the most, and the middle class earns in the middle of the two. The population is often divided into socio-economic groups based on their household incomes. The lower class, also known as the working class, is the socio-economic group with the least income. They are often categorized as families whose income falls below poverty line.The upper class is usually the smallest group among the three. However, it is bigger than most people expect, this is mainly because people only consider the uber-rich as upper class, whereas the truth of the matter is that anyone who has an income over the margin line is qualified to be called upper class, no matter if they seem to be or not.