What is an ISBN?

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What is the ISBN?

The ISBN is the International Standard Book Number, which is unique to every book. It identifies the publisher, country, author, title, and edition of a book. The International Standards Organization (ISO) determined a standardized system was necessary to help organize literary works offered by publishers. An ISBN allows anyone familiar with the system to determine the origin of the title including the geographical region published and publishing company. Automated sales systems depend on ISBN numbers to quickly manage sales and shipments of literary works.


The 10-digit ISBN format was developed by the International Organization for Standardization (ISO) and was published in 1970 as international standard ISO 2108. Since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with "Bookland" EAN-13s. Numbers of titles published prior to 2007 contain ten digits while more recent titles have a thirteen digit ISBN.


The 13 digit ISBN separates into 5 parts (in order):

  1. Prefix - As of 2011, all the 13-digit ISBNs begin with 978. As the 978 ISBN supply is exhausted, the 979 prefix will be introduced. Part of the 979 prefix is reserved for use with the Musicland code for musical scores with an ISMN.
  2. Registration Group is a 1 to 5 digit number. 1-English speaking; 2-French; 3-German; 5-Russian; 7-Chinese.
  3. Registrant – Publisher.
  4. Publication – Unique to that particular item.
  5. Check digit - form of redundancy check used for error detection, the decimal equivalent of a binary check bit. It consists of a single digit computed from the other digits in the message.

10 Digit ISBN vs. 13 Digit ISBN

Until the time comes that all 10 digit ISBN’s are exhausted, most materials will have both a 10 digit and a 13 digit ISBN. Generally, either ISBN is sufficient to provide to either the Bookstore or a publisher.

Relationship Between ISBN-10 and ISBN-13

Most 13 digit ISBN numbers for new books are simply the 10 digit ISBN with a “978” preceding it and the last number being different. The last number is different because it is a check digit that is calculated based on a formula applied to all the other digits in the ISBN. Used versions of the same book used to be differentiated from new books solely with a 99990 appearing after the ISBN. New books would instead have a 90000 after the ISBN. Some used books are now beginning to appear with a 13 digit ISBN that differentiates it from the new book ISBN by replacing the 978 with a 290.

International Standard Serial Number (ISSN) - Identifies periodical publications such as magazines.