Internationalizing Domain Names in Applications (IDNA)
Internationalized Domain Names (IDN) use Unicode for domain name, rather than using a subset of ASCII. This increased name space, as well the requirement to maintain compatibility with the existing domain name service means that IDNs must be encoded in a form that can be supported without changes to any portion of the DNS that does not participate in the upgrade to IDN. This specification defines a mechanism called IDNA for handling them in a standard fashion and specifies an IDNA profile for domain names used as host references. IDNA allows non-ASCII characters to be represented using the same octets used in so-called host names today. This representation allows IDNs to be introduced with minimal changes to the existing DNS infrastructure. IDNA is only meant for processing domain names, not free text.