How ISBNs Work

An International Standard Book Number (ISBN) is allocated to each book title rather than its subject or genre. Why?

ISBNs have ten digits split into four parts usually with hyphens. The first part tells you the language or the country. The second part is the publisher's code. The third digit refers to the title of the book and the last digit is used by computers to detect typing errors in the rest of the code.

Because sometimes different books have the same title. If you know an ISBN, you can be sure to get the book you intended - important if you buy on-line or place an order in a bookshop. It also means you don't have to worry about spelling mistakes in the title or an author's name!

ISBN

  • Always 10 digits with spaces or hyphens
  • Printed on the book (usually on the back)
  • Also bar code version
  • (ISBNs issued since January 2007 have 13 digits)

Dewey

  • 3 digits + decimal + digits without spaces or hyphens
  • Usually glued on spine