Bowker is the official source for purchasing ISBNs in the United States and we highly recommend registering your number through their system. It explains exactly which book is being bought and sold. Without an ISBN, you will not be found in most retail bookstores, libraries, or online marketplaces. With an ISBN, you can sell your book anywhere in the world. The barcode that will go on the back cover of your book is based on your ISBN number and we will be happy to create the barcode for you so it will be recognized by scanners at any retail outlet.
The International Standard Book Number, or ISBN, is the most important identifier you will link to your book which is made available for sale. ISBN numbers provide unique identification of your books and simplify the distribution of books throughout the global supply chain.