The ISBN (International Standard Book Number) is a unique, commercial book identifier. ISBNs come in 10-digit and 13-digit formats. The 13-digit codes were introduced in 2007 and so most new books will have this 13-digit code that begins with the digits 978.
Typically, you should be able to find this number on the CIP (Cataloging in Progress) page of the book which is often found directly after the title page. You can also find this information on the back cover of a book usually within or on top of a barcode. Books that are copyrighted before the 1970s will likely not have an ISBN number. Consult Worldcat.org to locate books in library catalogs around the world and to view associated ISBN numbers.
If you are interested in obtaining an ISBN for your book you should do so in one of the following ways: (1) Your book is assigned an ISBN by your publisher. If you are self-publishing the company you will publish through should be able to assign you a number. For example, if you were to use the company CreateSpace, a publish-on-demand company, you would input information on your book and ask it to assign you an ISBN which it would then do, allowing you to add it to your book before sending the manuscript. (2) Otherwise you have to purchase an ISBN from Bowker. To do that you go to myidentifiers.com and fill out the forms and make the payment.
NOTE: We frequently receive questions on how to find the ISBN number of a particular book. Due to limited staff, we are unable to respond to questions submitted related to determining the ISBN number of a book. Please consult worldcat.org to determine the ISBN number for a particular title.