The value and the need for an ISBN is something that authors must contend with as an expense without fully understanding what it is and why they need it.
To begin with, an ISBN stands for International Standard Book Number (ISBN) and is a numeric commercial book identifier that is intended to be unique. Publishers purchase ISBNs from an affiliate of the International ISBN Agency. This ISBN is assigned to every aspect of an author's book, eBook, audiobook, etc. Thus, when a bookstore, distributor, or a reader is trying to find the book or item, they can use the associated ISBN to find the item and additional information about the book and the author.
Without the ISBN, bookstores, and distributors would have a hard time finding the item and ordering it. As many authors know, Amazon can publish a book without the ISBN, but that means the book is only available for sale on Amazon and not in other locations. This limits the author's ability to be discovered by readers around the world. Over the past few years, Amazon’s publishing side has made ISBNs available for FREE with too many restrictions, and sadly authors are not reading about the restrictions or what it means to use the Amazon ISBN. Once again, leaving the author in no man’s land hurts their opportunity to be fully successful in the publishing world.
Other companies like Ingram and Draft2Digital are also offering FREE ISBN to win authors over and to have the author's books published with them. Giving them more income opportunities, while not fully disclosing the harm to authors who use this service.
An author that plans to write more than one book should seriously consider getting a set of 10 ISBNs from Bowker (Home | Bowker | Identifier Services (myidentifiers.com) is the main facility for creating and distributing ISBNs in the United States and some other countries as required. A 10-pack is usually the least expensive way to get all of the ISBNs an author will need to begin with.
Remember, for one title, you will need to have an ISBN for the paper book, eBook, audiobook, and other items as they become available.
Completing the information on Bowker about the title makes the book more easily discoverable for bookstores and distributors, as well as associating the ISBN with the printer like Amazon, Ingram, etc., for Print On Demand, which is the most economical way for authors to have books printed and available.
Even if an author does choose to have books printed in the hundreds or thousands, the ISBN will still help distributors and bookstores find the book and determine how to best purchase the book.
Another aspect to keep in mind for an author from a marketing perspective, but using the Bowker system to get your ISBN, the author's name and bio, along with the book is now in one more database for people to discover them. A small but simple marketing tool.
When an author does purchase the ISBN, Bowker does offer a barcode service that the author can take advantage of, or use a free service such as Tec-IT (Free Online Barcode Generator: ISBN 13 (tec-it.com), which can create the barcode in a variety of styles. The general and best-use style is the 13+5 number. There are 13 numbers of the ISBN, along with five digits that can reflect the retail price of the book. We recommend leaving this blank or with five zeros. The reason for the five zeros is that the price is not shown, and allows a bookstore to charge any price they want to for the book. If an author does show a retail price, most bookstores will cover that barcode with their sticker to reflect the sale price they are charging. By leaving it with five zeros, most bookstores will not need to cover the barcode. The key aspect is to have the 13-digit ISBN coded into the barcode for easy use for the distribution and sale of the book.