Every Chinese citizen has to carry a shenfenzheng (citizen’s card), which must be presented whenever proper identification is required. A shenfenzheng is valid for 10 years. Prior to expiration, citizens must report to their district PSB station for a new one. A citizen’s hukou (residence card) must be presented in order to reapply. The hukou assigns citizens to a specific area of residence and needs to be changed in order to move house or cities. Hukou is given at birth and doesn’t expire.­­­­