An Internationalized Domain Name (IDN) is a domain name containing characters outside the standard ASCII letter-digit-hyphen set, allowing registration in scripts like Cyrillic, Arabic, Chinese, Greek, and accented Latin letters. This enables native-language domain names worldwide.
IDNs work through Punycode encoding. When you register or use an IDN, the non-ASCII characters are converted to an ASCII-compatible format beginning with xn-- for DNS and HTTPS transport. For example, the domain münchen.de (with the umlaut ü) is stored in DNS as xn--mnchen-3ya.de. Browsers and applications automatically convert between the human-readable Unicode form and the encoded form, so users typically see the original characters.
How it works:
- A registrant registers a domain with non-ASCII characters at a domain registrar
- The registrar encodes the domain using Punycode (xn-- prefix added to each label)
- DNS stores and serves the encoded version
- Your browser decodes it back to Unicode for display
- SSL certificates and HTTPS requests use the Punycode form
Common examples:
日本.jp(Japan in Japanese) →xn--wgv71a.jpмосква.рф(Moscow in Russian) →xn--80akhbyknj4f.xn--p1aiمصر.eg(Egypt in Arabic) →xn--wgbh1c.eg
NoteIDN domains must still follow length and hyphenation rules (63 characters per label, 253 total), and some registries restrict which scripts are allowed at the top level. Always verify your target TLD's IDN policy before registering.