Language Tags

For users

What are language tags?
Why tagging?
Tag wisely
The Wikipedia article
Search the language registry
The excellent article from the W3C about language tags
Also from the W3C, a tutorial "Declaring Language in XHTML and HTML"
Another way to search subtags online in the registry (some explanations are provided, but this tool is more useful if you know the concepts behind the registry)
Browse language tags and see their meaning

For software developers

The subtag registry (version 2025-06-23) in various formats
Martin Dürst's implementation in Ruby is available as a Gem named "langtag" at RubyForge
Stéphane Bortzmeyer's implementation in Haskell.
Addison Phillips' code, as a regexp for Java
An implementation in XSLT (requires a XSLT 2.0 processor) and the Web page it powers (by Felix Sasaki).
Test suites

For standard authors

The current standard: RFC 5646 and RFC 4647
How to register a new subtag (for instance, for a variant of a language),
A syndication feed (Atom format) of the changes in the registry
Working on this Web site

To search a subtag, type a code or a description (for instance, "fr", or "german"):

Tout est aléa, confusion et précarité, sauf le Catalogue. (Fred Vargas)

Home. Web site maintained by webmaster@langtag.net.