Who was in the three estates of the old regime why was this system so unequal?

The three estates divided the social classes of Revolution Era France. There was an estate that had the wealth nobles, there was an estate that had church people in it, such as priests and bishops, and there was an estate that had the common people in it. It was unequal as the nobles lived comfortable lives in their palaces and the common people sometimes had to steal bread just to live.