Family register

A family register (also known in several variations, such as household register and family album, and, when discussing non-anglophone countries, the native-language names of the registers such as Familienbuch in Germany, hukou in mainland China and koseki in Japan) is a civil registry used in many countries to track information of a genealogical or family-centric legal interest.

Often, official recognition of certain events or status may only be granted when such event or status is registered in the family registry—for example, in Japan, a marriage is legally effective when and only when such filing is recorded into the household register (known as a koseki). In other cases, the family register serves as a centralized repository for family legal events, such as births, deaths, marriages, and expatriations, as with the familienbuch in use in Germany and the livret de famille () in France, although it is not the sole source of official recognition for such events.

Use of government-sanctioned or administered family registers, while common in many European nations and in countries which use continental-style civil law (where the family or household is legally viewed as the fundamental unit of a nation), is nonetheless rare in English-speaking countries (for example, the closest equivalent in the United Kingdom is the electoral roll, which is also organised by household, but it is limited in the amount of information recorded).

Although the United States for example assigns most citizens and residents a social security number intended to be unique to the recipient and information regarding birth, death and work history (in the form of contributions to the social security system) is collected, the U.S. social security system has long been intentionally restricted in the scope of information collected and maintained regarding individuals where not directly related to social security benefits—as such, no information is centrally collected regarding marriage, citizenship status, parentage, or the like, in contrast to the German and Japanese family register systems.

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