1. The concept of houses left over from history includes the problems left over from the socialist transformation of private houses, the problems of private houses occupied and confiscated during the Cultural Revolution, the problems of real estate entrustment in the early days of the founding of the People's Republic of China, and the implementation of private houses policies by overseas Chinese, compatriots from Hong Kong, Macao and Taiwan. 2. Illegal construction refers to illegal construction without the approval of the competent department.