alpha3

Alpha-3 refers to a class of three-letter codes used in international standardization to identify entities in a compact, machine-readable form. The term is most commonly associated with two ISO standards: ISO 3166-1 alpha-3 for countries and ISO 639-3 for languages. These three-letter codes are designed to be language-neutral, stable, and suitable for data interchange across borders and systems.

In ISO 3166-1, alpha-3 codes identify countries and certain geopolitical entities. Examples include USA for the United States, GBR for the United Kingdom, CAN for Canada, FRA for France, DEU for Germany, ESP for Spain, and JPN for Japan. The list also covers some international organizations and special areas; for instance, EUU has been used in reference to the European Union in some contexts. Codes are published and maintained by the ISO 3166 Maintenance Agency and are updated to reflect changes in sovereignty, borders, or status.

In ISO 639-3, alpha-3 codes identify natural languages. Examples include eng for English, spa for Spanish, fra for French, deu for German, zho for Chinese, and jpn for Japanese. The 639-3 set aims to cover all known languages, including minority, historical, and constructed languages, and is maintained by the ISO 639 Maintenance Group.

Alpha-3 codes are widely used in libraries, bibliographic databases, government data portals, geographic information systems, and various data schemas to enable consistent, interoperable tagging and lookup across languages and regions. See also ISO 3166-1 alpha-3 and ISO 639-3.