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ISBN (The International Standard Book Number) is a unique numeric book identifier based upon the 9-digit Standard Book Numbering (SBN) code created by Gordon Foster, Emeritus Professor of Statistics at Trinity College, Dublin, for the booksellers and stationers W. H. Smith and others 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. (However, the 9-digit SBN code was used in the United Kingdom until 1974.) An SBN may be converted to an ISBN by prepending the digit '0'. Currently, the ISO's TC 46/SC 9 is responsible for the ISBN. The ISO on-line facility only refers back to 1978.

Since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with Bookland EAN-13s.

An ISBN is assigned to each edition and variation (except reprintings) of a book, for example an ebook, a paperback, and a hardcover would each have a different ISBN. The ISBN is 13 digits long if assigned after 1 January 2007, and 10 digits long if assigned before 2007. An International Standard Book Number consists of 4 parts (if it is a 10 digit ISBN) or 5 parts (for a 13 digit ISBN).

The 13 digit ISBN separates its parts (prefix element, registration group, registrant, publication and check digit) with either a hyphen or a space. Other than the prefix element and the check digit, no part of the ISBN has a fixed number of digits.

Comparison to ISSN

A similar numeric identifier, the International Standard Serial Number (ISSN), identifies periodical publications such as magazines.

ISSN and ISBN codes are similar in concept, where ISBN numbers are assigned to individual books. For particular issues of a periodical an ISBN might be assigned in addition to the ISSN code for the periodical as a whole. Unlike the ISBN code, an ISSN is an anonymous identifier associated with a periodical title, containing no information as to the publisher or its location. For this reason, a new ISSN is assigned to a periodical each time it undergoes a major title change.


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