What is an ISBN?

Have you ever really wondered about that barcode on the back cover of your books. What exactly all those numbers mean? Well, I just read a rather interesting blog post over at The Private Library that broke down how that ISBN number / barcode translates into something a bit more understandable.


ISBN stands for "International Standard Book Number" and, according to Wikipedia, was originally a 10-digit format, developed by the International Organization for Standardization and was introduced in 1970. In 2007 the ISBN was expanded to 13 digits in order to be more universally compatible.
File:ISBN Details.svg
The ISBN can be broken down to 4 or 5 parts:
  1. In a 13 digit ISBN, the first three numbers are the prefix, in this case, 978 denoting book publishing
  2. The group identifier, indicating the language in which the particular book was published. 0 or 1 for English-speaking countries; 2 for French-speaking countries; 3 for German-speaking countries; 4 for Japan; 5 for Russian-speaking countries, 7 for People's Republic of China, etc.
  3. The publisher code, which can vary in length from 2 to 6 digits - The bigger the publisher, the smaller the code, and vice-versa. A list of Publisher codes can be found here.
  4. The item number, which represents the title of the book
  5. And a checksum character or check digit which enables a system to validate the rest of the number entered.  A lot of the time the values for the checksum will be 0, 9, or X.
So, my Harry Potter and the Sorcerer's Stone ISBN: 978-0-590-35340-3 tells me:


  1. It's a published book (978)
  2. Written in English (0)
  3. Published by Scholastic (590)
  4. What the ordering code is (35340) - check it out, go to the Scholastic Web site and enter 35340 into the search box to see what happens (btw, it won't work for Amazon, I tried).
So there you have it, the handy dandy function of the ISBN. Your life will never be the same, I know.

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