The International Standard Book Number, ISBN, is a unique commercial book identifier barcode. The ISBN system was created in the United Kingdom, in 1966, by the booksellers and stationers W.H. Smith.
Originally, it was the 9-digit Standard Book Numbering (SBN) code and still was used in 1974; it was adopted as the international standard ISO 2108 in 1970. A similar, numeric identification, the International Standard Serial Number (ISSN), identifies periodical publications such as magazines. Since January 1, 2007, ISBNs are of 13 digits, like in Bookland EAN-13. The TC 46/SC 9 is responsible for the standard.
An ISBN is given to each edition and variation (except reprintings) of a book. The ISBN is 13 digits long if assigned after January 1, 2007, and 10 digits long if assigned before 2007. An International Standard Book Number consists of 4 or 5 parts:
The group identifier code (GIC) number is 0 or 1 for English-speaking countries; 2 for French-speaking countries; 3 for German-speaking countries; 4 for Japanese; 5 for Russian, et cetera. The original standard book number (SBN) had no group identifier, but affixing a zero (0) as prefix to a 9-digit SBN creates a valid 10-digit ISBN. The group identifier may be up to 5 digits long; e.g. 99936 is a group identifier for the country Bhutan.
The national ISBN agency assigns the publisher number (cf. the category: ISBN agencies); the publisher selects the item number. Generally, a book publisher is not required to assign an ISBN, nor for a book to display its number (except in China; see below), however, most book stores only handle ISBN bearing merchandise.
A listing of all the 628,000 assigned publisher codes is published, and can be ordered in book form, but, as of 2007, it costs US$300. The web site of the international ISBN agency does not offer any free method of looking up publisher codes.