IDN domains (internationalized domains) are usually known as ""umlaut domains"" and have been in use since 2003. These allow the use of special characters, such as umlauts or accents, in addition to the standard ASCII characters. For example, Mr Thaddäus Müller can use the internet address www.thaddäus-müller.ch for himself; and you’d probably agree that it looks much better than www.thaddaeus-mueller.ch.
Is it always possible to use IDN domains?
No. It depends on the respective Top Level Domain (TLD). Many TLDs do not yet support special characters. Even where a TLD allows special characters, not all of the 90+ special characters are allowed.
For .ch domains, for example, the special characters ""ä, ö, ü, é, è, à, ê, ç"" are possible, but the special character ""ß"" is only allowed in Germany.
How do IDN domains work?
When the domain is accessed, it is encoded in the background via Punycode using ASCII-compatible coding format. This process removes all ""non-ASCII characters"" from the domain and places them in coded form at the end of the domain. In addition, the domain name is preceded by the character combination ""xn--"" to indicate that it is an IDN domain.
For example, the IDN ""tatütatatütatto.ch"" becomes the ACE string "xn--tattatatttattoo-1vbfb.ch"
Advantages of IDN domains
Improved readability: Words written with umlauts look more familiar, are less ""bulky"" and easier to read. Particularly in advertising media such as posters or flyers, the use of umlauts and special characters really stands out.
Downsides of IDN domains
There aren't many: Special characters look out of place in the address bar because they are not widely used. If you copy the address from the browser into a document or on social media, the domain is usually imported as an ACE string. Many users get the impression that the link is ""broken"".
Restricted user group: Special characters are country- or language-specific. ä, ö, ü, for example, exist only in the German language. This makes it difficult for users from other languages to access your website; the special characters simply do not exist on the keyboard.
Technical Issues: In theory, most applications should have no problems with IDN domains. Nevertheless there are CMS or e-mail programs which do not support IDN domains properly. Especially with e-mail, it must be ensured that the software of the sender as well as the recipient support IDN domains with the respective special characters.
So IDN domains are rubbish?
Not at all. You just need to be aware of the pros and cons. We recommend registering several domains. One without special characters and one with. For example, use the address ""*thaddaeus-mueller.ch"" as the primary domain so as to avoid all the downsides; i.e. for web as well as e-mail address. Use the address ""thaddäus-müller.ch"" to forward to the primary domain without umlauts. Thus, you can ideally use the umlaut domains for advertising purposes.