isbntools.com
FAQ
What is an ISBN?
An ISBN is a 10-digit or 13-digit number that identifies a book for purposes of commerce and supply chains. The last digit of the ISBN is a check digit used to detect transcription errors. This last digit is sometimes an "x".
13 digit ISBNs began to appear on January 1 2005, and all ISBN systems are required to support 13 digits by January 1, 2007.
The first number or numbers of a 10 digit ISBN identifies the country that issued the publishers prefix; this number is followed by a dash and the publisher prefix. 13-digit ISBN's start with either 978 or 979, and the 9 digits that follow correspond to the first 9 digits of a 10-digit ISBN.
The dashes (or spaces) in the ISBN occur in different places depending on the number and are meaningful, but are so frequently omitted that you can't really use the dashes for much. If you're really interested, here are the Gory Details
What is an ISBN barcode?
There are two types of isbn barcodes, the 10-digit ISBN and the 13-digit UPC with prefix 978 or 979 (a new prefix is planned). To get the 10 digit isbn from the upc, remove the 978 and the last digit (a check digit) then recompute the isbn check digit using our java class. If the 13 digit isbn starts with 979, then there is no equivalent 10-digit ISBN. An explanation of the ISBN and UPC check digit algorithms is at Book Industry Study Group.
I want to sell my book on Amazon, how do I get an ISBN for it?
ISBN prefixes are issued to publishers by natioanl ISBN agencies. A list of the agencies is at www.isbn.org