International Standard Book Number

The International Standard Book Number (ISBN) is a numeric commercial book identifier which is intended to be unique.[lower-alpha 1][lower-alpha 2] Publishers purchase ISBNs from an affiliate of the International ISBN Agency.[1]

International Standard Book Number
A 13-digit ISBN, 978-3-16-148410-0, as represented by an EAN-13 bar code
AcronymISBN
OrganisationInternational ISBN Agency
Introduced1970; 51 years ago (1970)
No. of digits13 (formerly 10)
Check digitWeighted sum
Example978-3-16-148410-0
Websiteisbn-international.org

An ISBN is assigned to each separate edition and variation (except reprintings) of a publication. For example, an e-book, a paperback and a hardcover edition of the same book will each have a different ISBN. The ISBN is ten digits long if assigned before 2007, and thirteen digits long if assigned on or after 1 January 2007.[lower-alpha 3] The method of assigning an ISBN is nation-specific and varies between countries, often depending on how large the publishing industry is within a country.

The initial ISBN identification format was devised in 1967, based upon the 9-digit Standard Book Numbering (SBN) created in 1966. The 10-digit ISBN format was developed by the International Organization for Standardization (ISO) and was published in 1970 as international standard ISO 2108 (the 9-digit SBN code can be converted to a 10-digit ISBN by prefixing it with a zero digit '0').

Privately published books sometimes appear without an ISBN. The International ISBN Agency sometimes assigns such books ISBNs on its own initiative.[3]

Another identifier, the International Standard Serial Number (ISSN), identifies periodical publications such as magazines and newspapers. The International Standard Music Number (ISMN) covers musical scores.