The person number of the household registration book is a set of unique numbers corresponding to the ID number, which has no function in itself and is only used for archiving. Just like opening an account in a bank, there is a set of account numbers on it, and the bank has a contract number and a process number, all of which correspond to this account number.

Legal basis: Article 7 of the Regulations on Household Registration in People's Republic of China (PRC) China's current household registration system includes seven registration systems: permanent residence, temporary residence, birth, death, emigration, immigration, change and correction. The registration of resident population is mainly to grasp the basic situation of resident population. Other changes in registration are mainly to grasp the changes in population. These basic registration systems are a unified whole, and without them, it is impossible to grasp the whole picture of the population.