Are Domain Names Limited to ASCII Characters and Numerals?

Many domain extensions are beginning to support Internationalized Domain Names which support character sets such as Chinese, Arabic, Cyrillic, or any other characters outside the US-centric ASCII characters.

See for more details.

Additional Reference

ASCII (American Standard Code for Information Interchange) is the most common character encoding format for text data in computers and on the internet.

In standard ASCII-encoded data, there are unique values for 128 alphabetic, numeric or special additional characters and control codes.