An ISBN is a unique 10 character ID number given to every book. Look on the back of your book for something like this example and look for the 10 digit number above the bar code. If you cannot locate your book's ISBN on the outside of the book, open the front cover and look on the page immediately following the title page. This should be the copyright page and will include information about the copyright date, the author and publisher. The ISBN should be in the middle or at the bottom of that page.