The International Standard Book Number (ISBN) is a numerical book identifier The 10-digit ISBN format was published as an international standard (ISO 2108) in 1970. Since 2007, the ISBN has 13 digits, Periodical publications such as magazines are identified by the similar International Standard Serial Number (ISSN).
An ISBN is assigned to each edition and variation (except reprintings) of a book, and has 4 or 5 parts:
- a 13-digit ISBN has a GS1 prefix: 978 or 979
- a group identifier, (language-sharing country group) this is 0 or 1 for English-speaking countries; 2 for French-speaking countries; etc.
- the publisher code,
- the item number, and
- a checksum character or check digit.