What is an ISBN?

An ISBN (International Standard Book Number) is a 13-digit number that identifies a specific edition and format of a book. Retailers, distributors and libraries use it to find, order and track that exact version.

What the digits mean

A 13-digit ISBN has 5 parts:

1. A prefix: 978 or 979
2. A registration group, for a country or language area
3. A registrant element, which identifies the publisher
4. A publication element, which identifies the specific book
5. A check digit, calculated from the other 12 digits to catch typing errors

The parts vary in length, so ISBNs are often printed with hyphens between them. Our ISBNs start with 979. See Why does my ISBN start with 979?.

ISBNs assigned before 2007 had 10 digits. See What's the difference between ISBN-10 and ISBN-13?.

A separate ISBN for each format

Each format of a book needs its own ISBN. The paperback, hardcover, ebook and audiobook of the same book each have a different ISBN. See How many ISBNs do I need?.

Who issues ISBNs

ISBNs are issued by national ISBN agencies, each responsible for its own country or region. Bowker is the agency for the United States, and our ISBNs are registered with Bowker.

What an ISBN doesn't do

An ISBN identifies your book. It doesn't give you any rights to its content or protect it from copying. Copyright does that. See How does copyright registration work?.

Where to look up an ISBN

Bookwire, Bowker's public ISBN database, is the only authoritative ISBN search. If a book is on Bookwire, its registration is correct. See What is Bookwire?.

On a printed book, the ISBN usually also appears as a barcode on the back cover. See Generate a barcode.