National identification number
Overview
 
A national identification number, national identity number, or national insurance number is used by the government
Government
Government refers to the legislators, administrators, and arbitrators in the administrative bureaucracy who control a state at a given time, and to the system of government by which they are organized...

s of many countries as a means of tracking their citizens, permanent residents, and temporary residents for the purposes of work, taxation, government benefits
Employee benefit
Employee benefits and benefits in kind are various non-wage compensations provided to employees in addition to their normal wages or salaries...

, health care
Health care
Health care is the diagnosis, treatment, and prevention of disease, illness, injury, and other physical and mental impairments in humans. Health care is delivered by practitioners in medicine, chiropractic, dentistry, nursing, pharmacy, allied health, and other care providers...

, and other governmentally-related functions. Sometimes, the number will appear on an identity card
Identity document
An identity document is any document which may be used to verify aspects of a person's personal identity. If issued in the form of a small, mostly standard-sized card, it is usually called an identity card...

 issued by a country.

The ways in which such a system is implemented are dependent on the country, but in most cases, a citizen is issued a number at birth or when they reach a legal age (typically the age of 18).
 
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