International Standard Book Number

The International Standard Book Number (ISBN) is a uniqueTemplate:Efn Template:Efn numeric commercial book identifier. Publishers purchase ISBNs from an affiliate of the International ISBN Agency.^[1]

An ISBN is assigned to each edition and variation (except reprintings) of a book. For example, an e-book, a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, and 10 digits long if assigned before 2007. The method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country.

The initial ISBN configuration of recognition was generated 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 SBN code can be converted to a ten digit ISBN by prefixing it with a zero).

Privately published books sometimes appear without an ISBN. The International ISBN agency sometimes assigns such books ISBNs on its own initiative.^[2]

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