You did the hard part. You wrote your book. Now it’s time to publish it. But what’s this? Vendors want an ISBN from you. What even is that? Do you really need one? Where do you get it?

ISBNs look kind of scary because they’re so legal-ish and computer-y. And that barcode? Wasn’t that the thing predicted in Armageddon? Or Revelations? Yikes!

Let’s tackle two questions first—which are really the same question:

What is an ISBN, and Do You Need One?

An ISBN is nothing more than an identification number, very specific to your physical book. It was created to help book retailers at the cash register, so they didn’t have to type in the title and edition every time someone buys the book. All that info is in the ISBN, which is encoded into the barcode, which they scan at the register. The ISBN also helps retailers reorder more of your book.

One reason it’s needed is because many books can have the same title. The content of a book can be copyrighted, but not its title. Fifty books may have the same title.

At the bookstore you choose The Greats of Wrath in paperback (you’re a fan of monsters through history). It also comes in hardcover, audiobook, and Kindle. You give your choice to the cashier, who scans the barcode, which renders the ISBN, which tells him what you bought, how much to charge you, and which book to replace in his inventory. If he just wrote down the title, the whole process could go awry.

The same thing happens when you buy socks at Target. You may choose the long green socks, instead of the short green ones or the long ones with green stripes or the long green ones with toes. The cashier scans the barcode, and the barcode gives the ID number for that item, the fancy cash register looks it up, and you pay for exactly what you got. It may also help Target replace that exact item in its inventory. It prevents errors, like you might get if you just wrote “green socks” on a receipt.

It’d be really easy to accidentally reorder 100 hardbacks when you wanted paperbacks. Expensive mistake. ISBNs prevent that, because the hardback and paperback have different ISBNs. It makes a retailer’s job easier.

That’s all ISBNs do. They don’t offer copyright protection. They don’t make you legit. Anyone can buy an ISBN, and most vendors give them away free.

The ISBN record includes the title, author, book format (paperback? hardcover?), size, and a bunch more specific details. But that’s all it does: store information.

So What Does the Barcode Do?

Look at one. You can see it. The barcode is simply the ISBN and the book price, represented by a symbol that computer scanners can understand. If we didn’t have scanners, the barcode would be useless. If scanners could read the ISBN and the price as text right off the book, we wouldn’t need barcodes. It simply saves the cashier from hand-typing the ISBN and price.

Does my Book Need a Barcode?

Finally, a straight answer!

Maybe!

Yes you do need a barcode, if it is a print edition someone could hold in their hands and which might be sold in a bookstore. Any book someone might want to scan with their scanner benefits from a barcode. Retailers may reject your book if it doesn’t have one, because they’re too busy to type in the titles.

No you don’t need a barcode if you are only going to sell your book out of the trunk of your car, or give it away to friends and family. None of your friends has a retail scanner. And even if they did, your book wouldn’t be in their database.

And if you don’t need a barcode, you don’t need an ISBN. Because remember, that’s all the barcode does.

Does my eBook Need an ISBN?

No. Vendors used ISBNs for a while for eBooks, because it was a perfectly good identification system. But an ISBN is long and cumbersome — most of the digits refer to the publisher, not your book. (See below for what an ISBN really means.)

So Amazon, being Amazon, made up their own system to identify eBooks. Kindle users download eBooks directly to their device, and Amazon keeps track on their end what was sold. Since there is nothing physical to scan and you didn’t even go to a store, there is no need for a barcode.

Soon thereafter, Apple’s iBookstore stopped requiring ISBNs for eBooks. Now, nobody asks for one. So for eBooks, at least, you’re off the hook.

And remember: no ISBN? No barcode. Because all the barcode does is represent the ISBN in a scannable way.

Say It Like the Cool Kids

ISBN is an acronym for International Standard Book Number. Makes sense, now that you know what it does. But notice that “Number” is in the acronym. So don’t say “ISBN number,” because that’s saying International Standard Book Number number. And now you know better.

How Can I Get a Free ISBN?

The KDP Amazon publishing platform cheerfully offers you a free ISBN. It comes with a catch, but it’s a fair enough catch: you can only sell that edition from Amazon. That is, you can’t use that same ISBN with another publisher, like IngramSpark or LightningSource or Lulu. If for some reason you want all three platforms to publish your book, you’d need a unique ISBN from each of them because, as you can learn below, the ISBN also identifies the publisher.

Should I Buy My Own ISBN?

If you want the freedom to print anywhere with a single ISBN, you can apply for an ISBN on your own at myidentifiers.com, run by Bowkers, the agency that manages the ISBN database in the United States. As of this writing they cost $125 each, and you fill out all the details online. (That’s a whole ‘nuther tutorial.)

If you are one of our authors, we can register an independent ISBN for you for just $59, and we’ll handle all the paperwork.

What’s the Difference between ISBN-10 and ISBN-13?

Back in cave man days, ISBNs had only 10 digits. Then came Amazon and the rest, helping anyone with a cat to write a book about it, and the system suddenly overloaded. So they invented ISBN-13, and in the process revamped what the digits stand for. ISBN-10 is old and outdated and redundant. And redundant. You don’t need both: the old numbers were converted to the new ISBN-13 system. So don’t put an ISBN-10 in your copyright page. It doesn’t help.

What Does an ISBN Represent?

I thought you’d never ask! Which is why I put this section at the end.

The paperback edition of my book Of Mice and Me was assigned this ISBN:

978-1–62660–130-7

That’s my barcode at the top of this story.

Each hyphenated group has a meaning, more or less. The first, 978, is an elusive number that only the Illiterati and members of the Trilateral Commission know about. Seriously, it’s mostly just a placeholder. Might as well be 000. When numbers began to run out, they added the prefix 979, which so far only Amazon uses.

The next group of digits tells you what country you’re in: the language group.

After that hyphen, the number above, 62660, belongs to the publisher, Prairie Moon Publishing. All Prairie Moon books have 62660 in the ISBN.

130 is specifically assigned to the book itself, in this case the paperback edition of Of Mice and Me. The hardback edition would have a different number. Every edition would have a unique number here.

The last digit is a mathematical check digit. I have no idea how the math works or whether it really checks anything. But that’s what I read on the internet.

All these numbers are represented in a scannable way using the barcode. Most barcodes also include the price. In my example at the top of this story, it’s “51395.” The book is $13.95, and the initial 5 represents the currency: US dollars.

So now you know everything about ISBNs. Go impress people at parties.