ISBN stands for something blah like "International Standard Book Number" (which might be right, or might not, because I'm totally guessing) but that is what makes a book "real." It's not the paper or the cover, tho those totally help in the "real"-making, but e-books, which have covers and type, but no paper, have ISBNs. The ISBN identifies the book to the public, and to bookstores and to anybody who wants to know about a book. Two books can have the same cover. Two authors can have the same name (which is frowned upon, but happens). Many, many books have the same plots. (FYI, there are only 16 plots. Or maybe only three. Depends on who you ask.)
But no book will ever, ever, ever have the same ISBN. It identifies one book and one book only. MINE. What is this secret number, you ask? Well, first of all, it's NOT a secret. (Share this news with your friends.) And secondly, there are actually two numbers. There are so many books, the ISBN people are switching from a 10-digit number to a 13-digit number.
That said, Here they are:
Oh, and I'll be posting a pre-pre-order excerpt from the book for my newsletter sometime next month, probably (depending on when I can remember to do it, and if I don't, nag me, 'kay?), so if you're not signed up for the newsletter and you want to be, send me an e-mail with "Subscribe" in the subject line, and I'll sign you up.