What is an umlaut domain?
An umlaut domain is an Internet address that, in addition to letters of the Latin alphabet and numbers, may also contain special characters, for example the German umlauts ä, ö and ü, the letter ß and other characters. Umlaut domains are therefore also called special character domains or IDN. The abbreviation stands for the English term internationalized domain name. Since the use of an umlaut domain is associated with disadvantages with regard to the range through a limited circle of users and technical difficulties can occur, their distribution is low. IDN domains account for only around 4 % of all registered domains.
Registry decides on permissible characters
In principle, almost all characters from the standardized Unicode character set are also possible in an umlaut domain. A list of IDN-compatible characters is available at unicode.org.
According to the IDN character list of DENIC, 93 special characters are allowed. There are separate registries for the new top-level domains, for example dotBerlin for .berlin. They have their own, often more restricted sets of rules.
Use with risks
When using umlaut domains, especially in the commercial sector, it is necessary to weigh up the technical disadvantages and the advantages in terms of availability and readability.
Another reason is the better readability. Bäckerei Müller simply looks more familiar than Baeckerei Mueller, and Suessoelgefaess, if the word exists at all, is hardly recognizable after dissolving the umlauts and the ligature ß. However, the familiar appearance of the name is over when umlaut domains are converted into a format suitable for the Internet.
The handy address bäckerei-müller.de then becomes xn--bckerei-mller-bfb28a.de. And that is really no longer self-speaking. However, such a translation of umlaut domains is necessary, for example so that links work. If this were not the case, backlinks would possibly be lost or the content would not be shared as frequently in social media. Both of these have a negative impact on search engine rankings. Technical difficulties are not excluded despite the conversion, because some browsers resolve umlauts or the ß directly when typing in ae, oe, ue or ss. Wrong page impressions are preprogrammed: neustrasse.de and neustraße.de lead to completely different websites.
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