Language code

A language code is a code that assigns letters or numbers as identifiers for languages. These codes are often used to organize library collections, to choose the correct localizations and translations in computing, and as a shorthand designation for forms. Language code schemes attempt to classify within the complex world of human languages, dialects, and variants. Most schemes make some compromises between being general enough to be useful and complete enough to support specific dialects.

Some common language code schemes include:

ISO 639 - The original ISO standard from 1967 to 2002. Now obsolete, it was replaced by ISO 639-1, ISO 639-2, and ISO 639-3. Sometimes used as a shorthand for the union of all 639 standard codes.

ISO 639-1 - Two-letter code system made official in 2002, containing 136 codes. Many systems use two-letter ISO 639-1 codes supplemented by three-letter ISO 639-2 codes when no two-letter code is applicable.

ISO 639-2 - Three-letter system of 464 codes.

ISO 639-3 - An extension of ISO 639-2 to cover all known, living or dead, spoken or written languages in 7,589 entries.

Old SIL codes - Codes created for use in the Ethnologue, a publication of SIL International that lists language statistics. The publication now uses ISO 639-3 codes.

IETF language tag - An IETF best practice, currently specified by RFC 4646 and RFC 4647, for language tags easy to parse by computer. The tag system is extensible to region, dialect, and private designations.

Verbix Language Codes - Constructed codes starting with old SIL codes and adding more information.