There are four RFCs that describe how to IDN.
- [RFC3454] - Preparation of Internationalized Strings ("stringprep")
- [RFC3490] - Internationalizing Domain Names in Applications (IDNA)
- [RFC3491] - Nameprep: A Stringprep Profile for Internationalized Domain Names (IDN)
- [RFC3492] - Punycode: A Bootstring encoding of Unicode for Internationalized Domain Names in Applications (IDNA)