IDnummer

An IDnummer, or identification number, is a unique numeric or alphanumeric code assigned by a government agency or other authoritative body to an individual to enable reliable identification within administrative systems. It is used to link records across government and private databases and to verify eligibility for services such as taxation, social security, healthcare, education, voting, and banking. In some countries, the same number is used across many services; in others, separate numbers or identifiers exist for different sectors. The structure of an IDnummer varies: some are purely random, others embed biographical data such as date of birth, and many include a check digit to detect input errors.

Examples of well-known identification numbers include Sweden’s personnummer, Norway’s fødselsnummer, Denmark’s CPR-number, Finland’s henkilötunnus, the Netherlands’ BSN, the United Kingdom’s National Insurance number, and the United States’ Social Security Number. Some jurisdictions use alphanumeric formats or include country codes, while others issue temporary or anonymized numbers for particular programs. Organizations may also assign internal ID numbers to customers or employees.

Because IDnumbers are central to identity verification, they are often protected by privacy and data protection laws. Unauthorized use, sharing, or leakage can lead to identity theft and fraud. Best practices include limiting exposure, using secure systems for storage and transmission, and allowing individuals to access and correct their records where required.

See also: national identification card, personal identity number, social security number, privacy and data protection.