This stands for “International Standard Book Number.” It’s meant to uniquely identify a printing of a text.

These are issued from the International ISBN Agency. They are sold through resellers, specific to each country.

The number has grown:

The first 3-digits of a current ISBN should always be “978.” This is to make the ISBN compatible with standard barcodes which are 13-digits. In a bar code, the first three digits are called the “European Article Number” or “International Article Number” and denote the country in which the manufacturer joined a GS1 Member Organization.

Books are always “978” because a fake country called “Bookland” was invented and assigned that number. This was done so that the same number could be prepended to a 10-digit ISBN to make it 13-digits and therefore compatible with other barcode systems.

An ISBN is unique to “publication.” So a hardcover, softcover, and electronic “printing” of a title will have different ISBNs.

The ISBN is owned by the publisher. So, if you republish a book under a different publisher (or you self-publish a previously published book), you will need to get a new ISBN.

The U.S. reseller of ISBN is R.R. Bowker LLC. A single ISBN currently costs $125. Publishers will normally buy them in blocks for much cheaper: a block of 10 is $300, and a block of 1,000 is $1,500.

Why I Looked It Up

I knew that an ISBN identified a book (I’ve published four), but I didn’t know specifics. As I was cataloging my library, I had to transcribe a bunch of ISBNs. I didn’t know the difference between the 10- and 13-digits, so I was copying them both, and it stuck me that the 13-digit was usually always the 10-digit, prefixed by “978.” So, I decided to investigate why.

Note: some of my 10- and 13-digit ISBNs are very different (not just the prefix), and I’m not totally sure why. It could be that I took the ISBN from the hardcover in one place and the softcover in another.


I was entering a new book into my library when I saw that its ISBN started “979.” I thought this might be a typo, but no – we ran out of 978s.

A Quick Guide to 979-ISBNs

In 2019, Bowker, the United States ISBN Agency, announced plans to use a new prefix, 979, due to diminishing inventory of 978-ISBNs. There are only so many unique combinations to be made from one prefix, so it became necessary to issue a new one.

Another important note: anything with a 979 ISBN doesn’t not have an equivalent 10-digit ISBN:

[…] this new 979-prefix does not have an equivalent ISBN-10 associated with it – it is not backwards-compatible and cannot be converted into an ISBN-10 counterpart.

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