Hukou
The government gives people benefits based on agricultural and non-agricultural residency status (often called rural and urban).  Urban residents got retirement pensions, education  and  health care, while rural people got none of those things. They had to build their own homes and grow their own food.  Migration inside China was  controlled by the government.  It was difficult to move from the country into a city.  People who moved without permission had to work in very bad conditions as they had no rights.