Currently Web addresses are typically expressed using Uniform Resource Identifiers or URIs. The URI syntax defined in RFC 3986 STD 66 (Uniform Resource Identifier (URI): Generic Syntax) essentially restricts Web addresses to a small number of characters: basically, just upper and lower case letters of the English alphabet, european numerals and a small number of symbols.
Recent developments enable you to add non-ASCII characters to Web addresses. This article provides a high level introduction to how this works. It is aimed at content authors and general users who want to understand the basics without too many gory technical details