What is an IDN or Internationalized Domain Name?

IDN (Internationalized Domain Name) is a domain name that can contain special characters (such as accented letters), or characters from non-Latin scripts (Arabic, Chinese, Cyrillic, etc…).

Since the birth of the Internet, domain names have long been restricted to Latin characters (A-Z), numbers and hyphens. With the introduction of internationalized domain names in 2003, the language barrier that forced many languages to adapt was lifted. IDNs paved the way for a universal Internet, accessible and representative of the world’s cultural and linguistic diversity.

In this article, we will explain how internationalized domain names work, their advantages, and the best practices for using them.

How does an IDN work?

Thanks to the IDNA (Internationalizing Domain Names in Applications) standard introduced in 2003, it is now possible to register domain names with accented letters (e.g.: é, ü, ñ), but also non-Latin scripts such as Cyrillic (русский), Arabic (العربية) or Chinese ideograms (中国), which are Unicode characters.

However, computer systems, especially the Domain Name System (DNS), which translates URLs into IP addresse, only works with standard ASCII (American Standard Code for Information Interchange) characters, and cannot read Unicode symbols.

To be understood by the DNS, IDNs are converted into ACE (ASCII Compatible Encoding), a coding syntax designed to translate IDNs. For example:

The IDN: www.παράδειγμα.gr (which means “example.gr”), becomes the ACE: www.xn--hxajbheg2az3al.gr

An IDN can also apply to the extension itself. This is called an internationalized extension. It is converted the same way into ACE. Here’s an example:

The IDN: www.παράδειγμα.ελ (which means “example.gr”, with .ελ, being the Greek equivalent of .gr), becomes the ACE: www.xn--hxajbheg2az3al.xn--qxam

ℹ️💡 ACE strings are composed of the prefix “xn–”, followed by Punycode. Punycode is a coding syntax that transforms the Unicode symbols of an IDN into an ASCII string.

This conversion is often invisible to the end user, who continues to see the original writing in their browser. It only allows DNS servers to properly display the web page.

What are the advantages of an IDN?

Enhance your identity and protect your brand

Registering your domain name usually comes once your brand is already established. If your brand contains accents or special characters, adopting an internationalized domain name allows you to stay true to your identity and avoid confusion between your brand and a competitor’s.

For a long time, dropping accents seemed inevitable. Yet this choice can have consequences, as removing an accent can completely change the meaning of a word. For example, a brand called “Chocolat corsé” (rich chocolate in French). Without the accent, the domain name chocolatcorse.fr could be mistaken for chocolate from Corsica.

💡 The best strategy to protect your brand is to register all versions of your domain name (accented and unaccented), then redirect the non-accented versions to your IDN.

This multi-registration strategy plays a preventive role: if a brand doesn’t register the accented variants of its domain name, a malicious third party could do so and divert traffic, or even mislead users. This is called “typosquatting”, and that’s exactly what happened with the launch of the French government’s site granddebat.fr(big debate in French) : another site with pornographic content quickly appeared at grandébat.fr (“grand ébat” = “big intercourse”)…

Some brands like Hermès, L’Oréal or Céline understood this well, registering accented IDN versions of their domain names and redirecting them to their main site. For example: loréal.com redirects to loreal.com.

Improve user experience and accessibility

A domain name is first and foremost an entry point to a website. The easier it is to remember, type and share, the smoother the navigation. Therefore, a domain name in your users’ language makes the experience more intuitive.

Between 2000 and 2021, the number of Internet users using non-Latin scripts has considerably grown: according to the latest Internet World Stats study, Chinese users increased by +2,650% and Arabic users by +9,348%.

These users may face difficulties accessing your site: their language uses a completely different alphabet from Latin, and their keyboard may not include the necessary characters. That’s why it’s important to make your site accessible to these audiences.

IDN help break down these language barriers by making domains available in all the world’s scripts. For example:

• A Spaniard will naturally type españa.es instead of espana.es
• A German will write münchen.de instead of muenchen.de
• A Russian will remember пример.рф more easily than its Latin transcription primer.ru

By adopting an IDN, a company builds trust and closeness with its audience, while making its site more inclusive and accessible to an international audience.

Boost local SEO to reach new markets

Search Engine Optimisation (SEO) relies partly on the match between users’ queries and website content. In our article “How to choose the right domain name?”, we also discuss the importance of keywords in domain names.

For SEO improvement, IDN are a powerful asset: they allow you to include exact keywords with accents and specific characters, especially in the target audience’s language. This means that when users search with their natural spelling, your site is more likely to appear at the top of results. Perfect for expanding into international markets!

You can also adopt a multi-domain strategy. The principle is simple: register several domain names to establish a strong local presence in different linguistic areas. This way, you gain visibility in local searches, and offer your users a site they can easily find in their preferred language.

💡 Don’t forget about internationalized extensions such as .ελ (Greece), or .рф (Russia), which directly use the local script and are often better indexed by local search engines.

What are the limitations and challenges of IDN?

Phishing risks and homograph attacks

Internationalized domain names initially suffered from a poor reputation. Why? Because they could be misused for homograph attacks: a form of phishing that involves creating a domain name similar to that of a well-known brand, business or organisation.

The issue comes from the similarity between certain characters from different alphabets. For example, the Cyrillic а is hard to distinguish from the Latin a. This is what the creator of the site аррӏе.com (xn--80ak6aa92e.com in ACE form) wanted to highlight: it is not Apple’s official website, even if it looks like it.

To protect users, some browsers such as Google Chrome warn them when they try to access suspicious sites. A warning message appears if the domain is deemed misleading, for example if it contains characters visually similar to others, or if its structure is close to a well-known domain. You can check Chrome’s criteria list to see how it distinguishes suspicious IDNs from legitimate ones.

Here is a screenshot of a Google Chrome warning when a user tries to access amàzón.com:

Still limited technical compatibility

Homograph attacks using IDNs are not the main online threat, but it’s still essential to protect users. For this reason, some registries prohibit the registration of domains combining characters from different scripts. Similarly, some extensions still don’t support IDN registrations, or are only partially compatible (accents are accepted, but non-Latin characters are not, for example).

At the same time, using IDN for email addresses (standard EAI: Email Address Internationalization) is still only partially supported by servers and email clients. Since a domain name is often used both for the website and for email addresses, it is recommended to check your email provider’s compatibility, and also register the ASCII equivalent version of the domain for your email addresses.

In the end, internationalized domain names are a fantastic opportunity to reach a global audience, make your sites more accessible and protect your brand. When used wisely, they become a real strategic asset for your online presence.

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