An IETF BCP 47 language tag is a standardized code or tag that is used to identify
human languages in the
Internet
The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a ''internetworking, network of networks'' that consists ...
. The tag structure has been standardized by the
Internet Engineering Task Force
The Internet Engineering Task Force (IETF) is a standards organization for the Internet and is responsible for the technical standards that make up the Internet protocol suite (TCP/IP). It has no formal membership roster or requirements and ...
(IETF) in ''Best Current Practice (BCP) 47''; the subtags are maintained by the ''
IANA Language Subtag Registry
The Internet Assigned Numbers Authority (IANA) is a standards organization that oversees global IP address allocation, autonomous system number allocation, root zone management in the Domain Name System (DNS), media types, and other Interne ...
''.
To distinguish language variants for
countries,
regions, or
writing systems
A writing system is a method of visually representing verbal communication, based on a script and a set of rules regulating its use. While both writing and speech are useful in conveying messages, writing differs in also being a reliable form ...
(scripts), IETF language tags combine subtags from other standards such as
ISO 639
ISO 639 is a set of standards by the International Organization for Standardization that is concerned with representation of names for languages and language groups.
It was also the name of the original standard, approved in 1967 (as ''ISO 639/ ...
,
ISO 15924,
ISO 3166-1
ISO 3166-1 (''Codes for the representation of names of countries and their subdivisions – Part 1: Country codes'') is a standard defining codes for the names of countries, dependent territories, and special areas of geographical interest. It ...
and
UN M.49.
For example, the tag "en" stands for
English; "es-419" for
Latin American Spanish; "rm-sursilv" for