Unicode in URLs Internationalized Resource Identifiers (IRIs) are a new protocol element, a complement to URIs [RFC2396]. An IRI is a sequence of characters from the Universal Character Set (Unicode/ISO10646).

Percent-encoding is a mechanism to encode 8-bit characters that have specific meaning in the context of URLs. It is sometimes called URL encoding. The encoding consists of substitution: A '%' followed by the hexadecimal representation of the ASCII value of the replace character.

UTF-8 is an encoding system for Unicode. It can translate any Unicode character to a matching unique binary string, and can also translate the binary string back to a Unicode character. This is the meaning of “UTF”, or “Unicode Transformation Format.”

Unicode is an international character encoding standard that provides a unique number for every character across languages and scripts, making almost all characters accessible across platforms, programs, and devices.