ISO 15924, Codes for the representation of names of scripts, defines two sets of codes for a number of writing systems (scripts). Each script is given both a four-letter code and a numeric one. A script is defined as "set of graphic characters used for the written form of one or more languages".
Where possible the codes are derived from ISO 639-2 where the name of a script and the name of a language using the script are identical (example: Gujarātī ISO 639 guj, ISO 15924 Gujr). Preference is given to the 639-2 Bibliographical codes, which is different from the otherwise often preferred use of the Terminological codes.
4-letter ISO 15924 codes are incorporated into the Language Subtag Registry for IETF language tags and so can be used in file formats that make use of such language tags. For example, they can be used in HTML and XML to help Web browsers determine which typeface to use for foreign text. This way one could differentiate, for example, between Serbian written in the Cyrillic (
sr-Cyrl) or Latin (
sr-Latn) script, or mark romanized text as such.
ISO appointed the Unicode Consortium as the Registration Authority (RA) for the standard. The RA is responsible for appointing a registrar who works with a Joint Advisory Committee (JAC) in developing and implementing the standard. The registrar from 2004 to 2018 was Michael Everson, and from January 2019 the registrar has been Markus Scherer, a technical director of the Unicode Consortium. The JAC consists of six members: one representative of the RA (Markus Scherer), one representative of ISO 639-2 (Randall K. Barry of the Library of Congress), one representative of ISO TC37 (Christian Galinski), one representative of ISO TC46 (Peeter Päll), and two representatives of ISO/IEC JTC 1/SC 2 (Rick McGowan and Ken Whistler, both also officers of the Unicode Consortium).
The following standards are referred to as indispensable by ISO 15924.
Around 160 scripts are defined in Unicode. Through a linkpin called "Property Value Alias", Unicode has made a 1:1 connection between a script defined, and its ISO 15924 standard. See Script (Unicode).