Punycode

Punycode is an ASCII-based encoding system used to convert internationalized domain names (IDNs) into a subset of ASCII containing only a-z, 0-9 and hyphens. It helps to ensure compatibility with existing Internet technologies and protocols that work only with ASCII characters, such as URL schemes, HTML, and DNS.

The Punycode is typically used in the preparation phase of domain name registration, when a domain name with international characters is entered into the Domain Name System (DNS). Rather than sending internationalized domain names directly to the DNS, the Punycode converts the characters into an ASCII compatible code by replacing non-ASCII characters with a set of letters and numbers. This result is called an “ace label”.

For example, the website www.español.com can be encoded as www.xn--espaol-zwa.com using Punycode. The same domain name would be represented in Unicode format as www.εσπανόλ.com.

Using Punycode helps ensure that domain names with internationalized characters are safe and secure when accessing them through a web browser. The ace label is recognized by many protocols and can be accessed by typing the URL or via a DNS lookup request.

Punycode is an important tool for creating internationalized domain names and ensuring seamless access to these resources. It is also of great importance for web security, since Punycode is used to ensure compatibility and prevent potential attacks that could result from accepting international characters in URLs.