If you want to sell your book in any retail outlet, whether it be a book chain, an independent shop, or an online source such as Amazon, or if you want your book in any library, it must have an International Standard Book Number (ISBN). Every country has a single agency responsible for issuing ISBNs. In the United States, the company is Bowker Identiﬁer Services.
Publishers—including self-publishers—may register their company and contact information with Bowker and order anywhere from one to one thousand ISBNs. Then when a specific number is assigned to a particular book, the publisher just goes to the Bowker website and registers the number and title. That guarantees that purchasers will be able to ﬁnd your book, and that the book will be listed in Books In Print, among other bibliographic resources. Don’t skip this step. The lack of an ISBN number marks the book and its author as rank amateurs.
Every book should have a number, and each number can be used only once. A new edition, or a different format will require a new number. Originally ISBNs had ten digits. In 1998, the numbers were expanded to a thirteen-digit format, with the ﬁrst three digits being 978. That will remain the case for the foreseeable future, but it provides for the possibility of change if all available numbers are exhausted. The numbers are broken into ﬁve parts of variable length. The ﬁrst three are always 978. The second section represents the country; the third, the publisher; the fourth, the title, and the ﬁfth, a code number that can be used to verify the other sections.
Most printing/publishing companies will offer to provide your book with its own ISBN, but that means that the book will be listed with the imprint of the production company: for example, Smashwords, or CreateSpace, or Lightning Source. If you want your own publishing company listed, you must purchase your ISBN directly from Bowker.
I had already decided that I want to publish under my own imprint, “Katzenhaus Books,” not the book production company, and that meant I had to procure my own ISBN number. Next decision: they sell one for $125.00 or ten for $250.00. It’s a bargain, right? But at the end of months of writing, I had reached the “never again stage” and wasn’t at all sure I would ever need more than one. After agonizing a bit, I opted to order ten, all the time feeling ridiculously extravagant.
Then I started checking on other matters. While I love print books and deﬁnitely want my book to be an object people can pick up and examine, I also love my Kindle. And I’m hopelessly infatuated with the new iPad. I wanted my book available in all available formats.
So what difference did that make? Well, you don’t have to have an ISBN for the Kindle edition, but you can provide one, and it’s useful if you plan to issue in several formats. And if you plan to publish an Apple version? You have to go through Smashwords, a company that formats your manuscript for all other e-book platforms (Sony, B&N, Palm, etc.). Smashwords requires an ISBN that is different from both the print version and the Kindle version. So I already needed three ISBNs for my single book. I actually saved myself $125.00 by ordering the set of ten.
Many bookstores also require books to have a printed barcode—also issued by Bowker. The barcode is a graphical representation of the book’s ISBN and its retail price. That decision is up to you, and it may be that your local bookstore will accept the book without a barcode. However they are relatively inexpensive, and they give the book that final published look.
Portions of the above blog have been taken from my book, "The Second Mouse Gets the Cheese: How to Avoid the Traps of Self-Publishing," available from Amazon, Barnes and Noble, Apple iBooks, and Smashwords.com.