ISO 639-1 is the first part of the ISO 639international-standardlanguage-code family. It consists of 136 two-letter codes used to identify the world's major languages. These codes are a useful international shorthand for indicating languages. For example:
Japanese is represented by ja (even though its endonym is Nihongo)
The ISO 639-1 list became an official standard in 2002, but had existed in draft format for some years before. The last code added was ht, representing Haitian Creole on 2003-02-26. The use of the standard was encouraged by IETF language tags, introduced in RFC 1766 in March 1995, and continued by RFC 3066 from January 2001 and RFC 4646 from September 2006. Infoterm (International Information Center for Terminology) is the registration authority for ISO 639-1 codes.
New ISO 639-1 codes are not added if an ISO 639-2 code exists, so systems that use ISO 639-1 and 639-2 codes, with 639-1 codes preferred, do not have to change existing codes.[1]
If an ISO 639-2 code that covers a group of languages is used, it might be overridden for some specific languages by a new ISO 639-1 code.
ISO 639-1 codes added after RFC publication in January 2001
