An internationalized domain name (IDN) is an Internet domain name that (potentially) contains non-ASCII characters. Such domain names could contain letters with diacritics, as required by many European languages, or characters from non-Latin scripts such as Arabic or Chinese. However, the standard for domain names does not allow such characters, and much work has gone into finding a way around this, either by changing the standard, or by agreeing a way to convert internationalized domain names into standard ASCII domain names. The latter method now appears to be the one that will be adopted, a system called Internationalizing Domain Names in Applications (IDNA) having been proposed, based on the Punycode ASCII encoding of Unicode strings.
In IDNA, the term internationalized domain name means specifically any domain name consisting only of labels to which the IDNA ToASCII algorithm can be successfully applied.