An International Standard Book Number (ISBN) is a 10 or 13-digit number that identifies a book product individually, and as belonging to a specific book publisher. The assignment of an ISBN number is essential for the international distribution of published books, and allows booksellers, public and academic libraries, book distributors and book wholesalers to process and handle your book information efficiently.

Every book publisher's ISBN now consists of 13 digits, divided into four parts of varying length, each separated by a hyphen, giving relevant parties the following information:

ie. 978-X-AAAAA-CCC-P (example for 13-digit ISBN)

1. (X) Group or country identifier - identifying the national or geographical grouping of a set of publishers;

2. (AAAAA) Book Publisher's identifier - identifying a particular book publisher within the group;

3. (CCC) Title identifier - identifying a particular book publisher's title or edition of a book publisher's title;

4. (P) Check digit - the single digit at the end of the ISBN which validates the book publisher's ISBN.