What is ASCII and what are ASCII vs. Non-ASCII characters in domains?
ASCII, pronounced ask-ee, stands for the American Standard Code for Information Interchange. ASCII was originally based on the English alphabet and consists of 128 characters including A-Z, 0-9, punctuation, spaces, and other control codes that can be found on a standard English keyboard. These 128 characters are then assigned a number from 0 to 127 to represent them in data transfer from one computer to the other. While ASCII code was originally developed for teletypewriters (a device used to send and receive messages), it found broader application with the development of personal computers.
ASCII and Non-ASCII Characters in Domain Names
ASCII domains, much like ASCII in general, is based on the English alphabet. These domains are limited to only include the following characters: A-Z, 0-9, and dashes (-). Other types of punctuation, spaces, etc. are not allowed for these domains. ASCII domains are much more prevalent than non-ASCII character domains currently as non-ASCII domains were only just recently made available for public registration (around 2010).
Examples of ASCII Character Domains
Common examples of ASCII characters used in domains:
Non-ASCII domains are commonly referred to as Internationalized Domain Names (IDNs). More recently, international domain extensions have also become available in a variety of languages and scripts. These types of domains allow for a much larger variety of characters to be included, which opens up the Internet to more people around the world through accessibility and use of other languages. In short, non-ASCII domains are not confined strictly to ASCII characters (A-Z, 0-9, and dashes), they allow for wide variety of unique characters.
Examples of Non-ASCII Characters
Examples of non-ascii characters used in international domain extensions: