What is an ISBN?
International Standard Book Number = ISBN
The International Standard Book Number (ISBN) is a numeric commercial book identifier which is intended to be unique. Publishers purchase ISBNs from an affiliate of the International ISBN Agency. An ISBN is assigned to each separate edition and variation (except reprintings) of a publication. For example, an e-book, a paperback and a hardcover edition of the same book will each have a different ISBN. The ISBN is ten digits long if assigned before 2007, and thirteen digits long if assigned on or after 1 January 2007. Wikipedia.org
Most publishing houses will provide these for you at a cost because there is some information they need to input into a central database regarding your book. I should also mention that getting a number and the cost (if there is one) will vary between countries.
Why do I need one? To sell my book. (simple) To track and record my book. To protect my product.
I decided to bulk buy my ISBN with Barcodes because I know I will write more than one book. Purchasing the codes directly ensures my book rights are protected and ownership belongs to me. Self-purchasing means I’m prepared to engage in any marketing opportunities made available.
I know I will have to enter the book data on the ISBN site myself rather than my publishing provider but I’m sure I’ll manage and by doing it myself, I’ll be saving myself money and it guarantees me ownership of my book. ( Not that I have any concerns regrading the publishing house I’m using, I’m merely stating a fact. There are scammer out there and it pays to protect yourself whenever you can.)
ISBN and Barcodes are essential if you want to operate and sell your product. You can purchase these numbers directly from registered broker or through a subsidiary that has approval to on-sell. Check what is appropriate for your country.
AND then: We have the QR codes. (Quick response codes) Some products, including books, now have these flowcodes. Is it something I need right now—not really. Will this be something I will have to consider in the future—probably. I mentioned them because I think this could be the way technology is heading.
NUTSHELL: To sell your book in any store or on a reputable site—you need one.