ISAN is a voluntary numbering system for the identification of audiovisual works. ISAN gives registered audiovisual works and related versions of works a unique, permanent, internationally recognized, reference number. ISAN is independent of any physical form (e.g. DVD, theatrical release print) in which the work exists or could be distributed (e.g. over-the-air broadcast, streaming over internet).

ISAN identifies individual audiovisual works, not publications, nor rightsholders and relates to specific descriptive metadata such as original and alternative titles, language, type, duration, cast etc.. This descriptive data, known as metadata, together with the ISAN, is centrally registered and globally administered by the ISAN International Agency (ISAN-IA) in Geneva.

ISAN is not a "content descriptor". It is a "dumb" number, meaning that it does not include any codes or other signifying elements. Its purpose is to identify the work with a unique number, not to provide, within the number itself, any type of descriptive information about the work. ISAN can be affixed to any work, digital or analogue.

ISAN is designed to be read by humans and processed in information systems, as a 24-bit hexadecimal number or as a 96-bit binary number, for easier systems integration.

The root section identifies a work throughout its existence whether it is a feature film, serial, documentary, live broadcast or any other type of work.

The episode section identifies parts of a serial work sharing a common root.

In the case of a different version of a work, for example another language, edit, or format, this can be indicated by using the version section.

Both the episode and version sections share a common root.