Internationalized Domain Names (IDNs) are domain names represented by local language characters. Such domain names could contain letters or characters from non-ASCII scripts (for example, Arabic or Chinese). Many efforts are ongoing in the Internet community to make domain names available in character sets other than ASCII.
These "internationalized domain name" (IDN) efforts were the subject of a 25 September 2000 resolution by the ICANN Board of Directors, which recognized "that it is important that the Internet evolve to be more accessible to those who do not use the ASCII character set," and also stressed that "the internationalization of the Internet's domain name system must be accomplished through standards that are open, non-proprietary, and fully compatible with the Internet's existing end-to-end model and that preserve globally unique naming in a universally resolvable public name space."
IDN stands for Internationalized Domain Name. IDNs are domain names represented by local language characters. Such domain names could contain characters with diacritical marks as required by many European languages, or characters from non-Latin scripts (for example, Arabic or Chinese). IDNs make the domain name label as it is displayed and viewed by the end user different from that transmitted in the DNS. To avoid confusion the following terminology is used: The A-label is what is transmitted in the DNS protocol and this is the ASCII-compatible (ACE) form of an IDNA string; for example "xn--11b5bs1di". The U-label is what should be displayed to the user and is the representation of the Internationalized Domain Name (IDN) in Unicode; Lastly, the LDH-label strictly refers to an all-ASCII label that obeys the "hostname" (LDH) conventions and that is not an IDN.