Work was begun on the ISO 639-2 standard in 1989, because the ISO 639-1 standard, which uses only two-letter codes for languages, is not able to accommodate a sufficient number of languages. The ISO 639-2 standard was first released in 1998. 

In practice, ISO 639-2 has largely been superseded by ISO 639-3 (2007), which includes codes for all the individual languages in ISO 639-2 plus many more. It also includes the special and reserved codes, and is designed not to conflict with ISO 639-2. ISO 639-3, however, does not include any of the collective languages in ISO 639-2; most of these are included in ISO 639-5.

Reserved for local use
Scopes and types
Collections of languages
History and relationship to other ISO 639 standards