Identity document

An identity document (abbreviated as ID) is a document proving a person's identity.

If the identity document is a plastic card it is called an identity card (abbreviated as IC or ID card). When the identity document incorporates a photographic portrait, it is called a photo ID. In some countries, identity documents may be compulsory to have or carry.

The identity document is used to connect a person to information about the person, often in a database. The connection between the identity document and database is based on personal information present on the document, such as the bearer's full name, birth date, address, an identification number, card number, gender, citizenship and more. A unique national identification number is the most secure way, but some countries lack such numbers or do not show them on identity documents.

In the absence of an explicit identity document, other documents such as driver's license may be accepted in many countries for identity verification. Some countries do not accept driver's licenses for identification, often because in those countries they do not expire as documents and can be old or easily forged. Most countries accept passports as a form of identification. Some countries require all people to have an identity document available at all times. Many countries require all foreigners to have a passport or occasionally a national identity card from their home country available at any time if they do not have a residence permit in the country.

A version of the passport considered to be the earliest identity document inscribed into law was introduced by King Henry V of England with the Safe Conducts Act 1414.

For the next 500 years up to the onset of the First World War, most people did not have or need an identity document.

Photographic identification appeared in 1876 but it did not become widely used until the early 20th century when photographs became part of passports and other ID documents, all of which came to be referred to as "photo IDs" in the late 20th century. Both Australia and Great Britain, for example, introduced the requirement for a photographic passport in 1915 after the so-called Lody spy scandal.

The shape and size of identity cards were standardized in 1985 by ISO/IEC 7810. Some modern identity documents are smart cards that include a difficult-to-forge embedded integrated circuit standardized in 1988 by ISO/IEC 7816. New technologies allow identity cards to contain biometric information, such as a photograph, face; hand, or iris measurements; or fingerprints. Many countries issue electronic identity cards.