Hukou (Chinese: 户口; lit. 'household individual'; IPA: [xû.kʰòʊ̯]) is a system of household registration used in the People's Republic of China. The system itself is more properly called huji (Chinese: 户籍; lit. 'household origin'; IPA: [xû.t͡ɕǐ]), and has origins in ancient China; hukou is the registration of an individual in the system. A household registration record officially identifies a person as a permanent resident of an area and includes identifying information such as name, parents, spouse and date of birth. A hukou can also refer to a family register in many contexts since the household register (simplified Chinese: 户口簿; traditional Chinese: 戶口簿; pinyin: hùkǒu bù) is issued per family, and usually includes the births, deaths, marriages, divorces, and moves, of all members in the family.

The system descends in part from ancient Chinese household registration systems. The hukou system also influenced similar systems within the public administration structures of neighboring East Asian countries, such as Japan (koseki) and Korea (hoju), as well as the Southeast Asian country Vietnam (hộ khẩu). In South Korea, the hoju system was abolished in January 2008. While unrelated in origin, propiska in the Soviet Union and resident registration in Russia had a similar purpose and served as a model for modern China's hukou system.

Due to its connection to social programs provided by the government, which assigns benefits based on agricultural and non-agricultural residency status (often referred to as rural and urban), the hukou system is sometimes likened to a form of caste system. It has been the source of much inequality over the decades since the establishment of the People's Republic of China in 1949, as urban residents received benefits that ranged from retirement pension to education to health care, while rural citizens were often left to fend for themselves. Since 1978, the central government has undertaken minor reforms of the system in response to protests and a changing economic system.

The formal name for the system is huji. Within the huji system, a hukou is the registered residency status of a particular individual in this system. However, the term hukou is used colloquially to refer to the entire system, and it has been adopted by English-language audiences to refer to both the huji system and an individual's hukou.

The hukou system has origins in China that date back to ancient times, but the system in its current form came into being with the 1958 People's Republic of China Hukou Registration Regulation.

Until very recently, each citizen was classified in an agricultural or non-agricultural hukou (commonly referred to as rural or urban) and further categorized by location of origin. This two-fold organization structure was linked to social policy, and those residents who held non-agricultural (i.e., urban) hukou status received benefits not available to their rural counterparts, and vice versa.

Internal migration was also tightly controlled by the central government, and only in the past few decades have these restrictions been loosened. While this system has played a major role in China's fast economic growth, hukou has also promoted and aggravated social stratification and contributed significantly to the deprivation of many of China's rural workers.

In recent years,^[when?] steps have been taken to alleviate the inequalities promulgated by the hukou system, with the most recent major reforms announced in March and July 2014, which included a provision that eliminated the division between agricultural and non-agricultural hukou status.