An ISBN is a 10- or 13-digit number that is used to identify a book from a specific publisher. Once your book is in print, you can register the title and link it to the ISBN here.

Do I need an ISBN?

Honestly? Not really.

You definitely need an ISBN if you’re planning to release the book through a distributor (like Diamond Comics Distributors) or to a retail outlet (like Amazon).

If you’re just selling books directly to readers through your site, you don’t need an ISBN.

Where do I get an ISBN?

I recommend that you buy your ISBNs from R.R. Bowker. POD companies may offer an ISBN, but if you buy it from a reseller, you take the risk that you may not be listed as the book’s actual publisher. CreateSpace is a notable exception. Their ISBNs are legit.

Where do I put my ISBN?

The ISBN is printed on your book’s copyright page, and it is incorporated into the barcode that should appear on the book’s back cover.

Barcodes

The ISBN is used (along with the retail price of the book) to create the barcode. You can create a barcode easily online or you can purchase software like Barcode Producer to create them.

The retail price is coded in a five-digit number.

• The first number denotes the currency: 5 is for U.S. currency, 4 is Canadian, and I’m not sure what the others are.
• The next four numbers represents the price in cents. In other words a $19.95 book is 1995

You print the barcode on your book as part of your back cover. Here are some guidelines —  including how to place it properly on the back cover.

More information

Here’s a ton more information on the topic. If you have the Webcomics Handbook, there’s information on ISBNs there, too.