Communism is a government that wants a classless, money less, and stateless social order. This means that there is no lower, middle or upper class. So there is no poor or rich, everybody is equal.
Strength and Weaknesses
One weakness of communism is that people don't have to work as hard to get the same amount of pay as others so they end up not working hard. Which means that the products they make are low quality. One strength is that there is a level of equality among all people. So no one is super rich and no one is really poor. Everyone is considered the same so there is no fighting for equality.