Internationalized Domain Name

An internationalized domain name (IDN) is an Internet domain name that contains at least one label that is displayed in software applications, in whole or in part, in a language-specific script or alphabet, such as Arabic, Chinese, Russian, Tamil or the Latin alphabet-based characters with diacritics, such as French. These writing systems are encoded by computers in multi-byte Unicode. Internationalized domain names are stored in the Domain Name System as ASCII strings using Punycode transcription.

The Domain Name System, which performs a lookup service to translate user-friendly names into network addresses for locating Internet resources, is restricted in practice to the use of ASCII characters, a practical limitation that initially set the standard for acceptable domain names. The internationalization of domain names is a technical solution to translate names written in language-native scripts into an ASCII text representation that is compatible with the Domain Name System. Internationalized domain names can only be used with applications that are specifically designed for such use; they require no changes in the infrastructure of the Internet.

IDN was originally proposed in December 1996 by Martin Dürst and implemented in 1998 by Tan Juay Kwang and Leong Kok Yong under the guidance of T.W. Tan. After much debate and many competing proposals, a system called Internationalizing Domain Names in Applications (IDNA) was adopted as a standard, and has been implemented in several top-level domains.

In IDNA, the term internationalized domain name means specifically any domain name consisting only of labels to which the IDNA ToASCII algorithm (see below) can be successfully applied. In March 2008, the IETF formed a new IDN working group to update the current IDNA protocol.

In October 2009, the Internet Corporation for Assigned Names and Numbers (ICANN) approved the creation of internationalized country code top-level domains (IDN ccTLDs) in the Internet that use the IDNA standard for native language scripts. In May 2010 the first IDN ccTLD were installed in the DNS root zone.