How can I get an International Standard Book Number (ISBN)?

ISBN's are International Standard Book Numbers, as you probably know, and they're internationally unique IDs for books and book-like works. To give you an idea of how these work, here's the ISBN for my recently book Wicked Cool Shell Scripts: ISBN 1-59327-012-7. This breaks down as country identifier: 1, publisher identifier: 59327, title identifier: 012, and check digit: 7.

Checking another book from the same publisher, Hacking: The Art of Exploitation, we can see that its ISBN is 1-59327-007-0, so indeed "59327" is the publisher ID and these books are #12 and #7, respectively.

The following detailed ISBN Q&A is directly from the ISBN clearinghouse organization, and it offers definitive answers on these questions.

What is the format of the ISBN?
Every ISBN consists of ten digits and whenever it is printed it is preceded by the letters ISBN. The ten-digit number is divided into four parts of variable length, each part separated by a hyphen.

Does the ISBN have any meaning imbedded in the numbers?
The four parts of an ISBN are as follows:

• Group or country identifier which identifies a national or geographic grouping of publishers;
• Publisher identifier which identifies a particular publisher within a group;
• Title identifier which identifies a particular title or edition of a title;
• Check digit is the single digit at the end of the ISBN which validates the ISBN.

Why do some ISBNs end in an "X"?
In the case of the check digit, the last digit of the ISBN, the upper case X can appear. The method of determining the check digit for the ISBN is the modulus 11 with the weighting factors 10 to 1. The Roman numeral X is used in lieu of 10 where ten would occur as a check digit.

Who assigns an ISBN?
ISBN are assigned by ISBN group agencies worldwide coordinated by the International ISBN Agency in Berlin. ISBNs are assigned in the United States by the U.S. ISBN Agency. R.R. Bowker is the independent agent in the U.S. for this system.

Who is eligible for an ISBN?
The ISBN Agency assigns ISBNs at the direct request of publishers, e-book publishers, audio cassette and video producers, software producers and museums and associations with publishing programs.

Your best bet to proceed with obtaining an ISBN is to read through the material on their site, then apply for an ISBN directly. It's $19.95 for 10 ISBN's if you don't require expedited processing, so it's quite reasonably priced.