What Is an ISBN and Why Does It Matter?

An ISBN (International Standard Book Number) is a unique 13-digit identifier assigned to each edition and variation of a book. It serves as the universal language of the book trade, allowing retailers, libraries, distributors, and databases to accurately identify and catalog your title. Without an ISBN, your book cannot be ordered through standard retail channels or listed in most online bookstores.

How to Obtain an ISBN

In the United States, ISBNs are issued exclusively through Bowker (myidentifiers.com). You can purchase a single ISBN or buy them in blocks of 10, 100, or 1,000 — with significant per-unit savings at higher quantities. Key points to remember:

Each format (hardcover, paperback, ebook) requires its own ISBN.
A revised edition with substantial changes needs a new ISBN.
The publisher of record on the ISBN is the entity listed as the publisher — if you use a third-party service’s ISBN, they appear as your publisher.
Barcodes are separate from ISBNs; you need both for retail distribution.

Common ISBN Mistakes to Avoid

Many first-time authors make errors that can complicate distribution later. Avoid reusing an ISBN across different formats, registering under the wrong publisher name, or skipping ISBN registration entirely for print editions you plan to sell beyond direct channels. If you are unsure about any aspect of the ISBN process, our team can walk you through it and ensure your book is set up correctly from the start.