What is an ISBN and is it important?
ISBN stands for International Standard Book Number￼. It’s that number with dashes you see on the opening pages of a book, right along with the publishers details and the author’s copyright. Every printed book in the world has one.
So what is it?
The ISBN is the book’s unique bar code, invented in the 1960s before barcodes were thought of. It serves, just like a barcode, as a unique identifier for the book, instantly searchable in catalogues by all and sundry. Who mostly uses ISBN’s are retailers, again for the same reasons as a barcode – to see what’s still in stock, order more and order new.
There are several components to an ISBN: not just a book serial number and author identifier, but also the publisher’s code and in what format it is printed. For example the same book with have different ISBNs for a print version and a digital version.
Do I need it?
If you are publishing print books, then you have to have an ISBN. The publisher normally arranges this, because they need it for their business.
In the world of digital books, some eBook retailers want it, like Barnes & Noble; others don’t much care (Apple); or they have their own internal codes anyway, like Amazon’s ASIN. Some third party aggregators or distributors want ISBNs also.
So if you want your book published across several vendors, in the different formats they insist on or can sell, most likely you will need an ISBN. Actually more than one, for remember it’s not your manuscript that is being ISBN’ed, it is the book itself – your manuscript and how it is presented.
Is it useful otherwise?
The easiest way to look at the value of ISBNs is to consider them as metadata, just like the keywords you associate with your book, the objective of which is to help people find your book as quickly as possible.
Where do you get ISBNs?
The normal route most authors take is to let their publisher worry about administrative things like this. Most digital book publishers offer this as a service. They still have to go somewhere to get the ISBN, since being unique this means a central authority must be issuing them. In each country there is an official agency charged with this. Some countries offer the service for free (e.g. India), others for an administrative fee (United Kingdom) and others assigned to companies for profit (USA). So not only do you have an ISBN for format, you have to decide the country from which you want it to be issued.
Are there other codes?
Yes, there is the European Article Number (EAN), the Digital Object Identifier (DOI) and the Universal Product Code (UPC). You don’t have to worry about them, so far.
You can see why this is not an easy choice to make. An ISBN is not necessary for a digital book, unless the publisher insists on it. It does help as part of properly structured metadata; although most readers would never think to search by ISBN, it is an industry standard, which means it has value in a larger market. Don’t forget you might need more than one ISBN though, simply because you sell your book as an iBook, an ePub3, a Mobi etc.
So can you publish a digital book without an ISBN and add it later? It’s a moving target. Some don’t want it (Amazon/Kindle), some insist on it up front (Barnes & Noble) and others let you modify your metadata as you need (Apple/iBooks and some aggregators). Best to know what you want first, I think.