ISO 639-1

Content sourced from Wikipedia, licensed under CC BY-SA 3.0.

ISO 639-1 is the first part of an international standard for language codes. It defines two-letter codes (set 1) to name languages. As of June 2021, there are 183 two-letter codes, covering many of the world’s major languages. Some languages don’t have a code because the standard focuses on well-established, major languages.

ISO 639-1 is more limited than the other parts of ISO 639 (such as ISO 639-2 and ISO 639-3), which cover more languages and variations. These codes are a convenient, universal shorthand for indicating languages. They’re often used in website addresses to label language versions, for example ja.wikipedia.org for Japanese. Country code top-level domains (like .jp) are not the same as these language prefixes.

ISO 639 was created in 1967. ISO 639-1 became the updated revision in 2002. The last code added was ht for Haitian Creole on February 26, 2003. The use of language tags was encouraged by IETF language tags, starting with RFC 1766 (1995) and followed by RFC 3066 (2001) and RFC 4646 (2006). The current applicable version is RFC 5646 (2009).

Infoterm (the International Information Center for Terminology) is the registration authority for ISO 639-1 codes. New 639-1 codes are not added if a corresponding ISO 639-2 (set 2) three-letter code exists, so systems using both standards can stay compatible. If a 639-2 code covers a group of languages, a new 639-1 code may override it for a specific language.

Part 3, ISO 639-3 (2007), aims to cover all known natural languages and largely supersedes ISO 639-2. It does not fully address macrolanguages (see ISO 639-3).

See also: IETF language tag.