What is ISBN?

ISBN, what is it? When I noticed a book listing an ISBN-10 and ISBN-13 number, I found myself asking what was going on.

So I did a little investigation. In 2007, they switched from an ISBN-10 to an ISBN-13, but recommended that books published in the transition period carry both.

But what is an ISBN? It stands for International Standard Book Number. Supposedly every book, professionally published, has been given a unique 10 digit ISBN, since the system started in 1970. Now that has been changed to 13 digits. Why? To better conform with the 13 digit EAN code, which is a bar code for all products.

So what does the code mean?
For example: ISBN# 978-81-7525766-0
978 - Is the EAN code for books.
81 - Is group code, such as identifying it as an English speaking country.
7525 - Identifies the publisher. A publisher may have more than one code.
766- Product number.
0 - Check sum. This number is arrived at by following a complex mathematical formula. You multiply all the numbers by a predetermined amount, add together the totals, and divide them by 11 or 10 depending if it is 10 or 13 ISBN. The number that remains is then added to the check sum number to equal 11 or 10. This is supposed to assure that there are no errors when typing numbers so that no invalid ISBN are issued.

So now you and I know a little bit more.