ISO 3166-1 alpha-2

ISO 3166-1 alpha-2 codes are two-letter country codes defined in ISO 3166-1, part of the ISO 3166 standard published by the International Organization for Standardization (ISO), to represent countries, dependent territories, and special areas of geographical interest. They are the most widely used of the country codes published by ISO (the others being alpha-3 and numeric), and are used most prominently for the Internet's country code top-level domains (with a few exceptions). They were first included as part of the ISO 3166 standard in its first edition in 1974.

Uses and applications

The ISO 3166-1 alpha-2 codes are used in different environments and are also part of other standards. In some cases they are not perfectly implemented.

Perfect implementations

The ISO 3166-1 alpha-2 codes are used in the following standards:

Imperfect implementations

Starting in 1985, ISO 3166-1 alpha-2 codes have been used in the Domain Name System as country code top-level domains (ccTLDs). The Internet Assigned Numbers Authority currently assigns the ccTLDs mostly following the alpha-2 codes, but with a few exceptions. For example, the United Kingdom, whose alpha-2 code is GB, uses .uk instead of .gb as its ccTLD, as UK is currently exceptionally reserved in ISO 3166-1 on the request of the United Kingdom.

ISO 3166-1

ISO 3166-1 is part of the ISO 3166 standard published by the International Organization for Standardization (ISO), and defines codes for the names of countries, dependent territories, and special areas of geographical interest. The official name of the standard is Codes for the representation of names of countries and their subdivisions – Part 1: Country codes. It defines three sets of country codes: