Structure of an ISBN

Every International Standard Book Number (ISBN) consists of ten digits and whenever it is printed the letters ISBN precedes it.

The Ten-Digit number is divided into four parts of variable length, each part when printed being separated by a hyphen or space.

The four parts are as follows:

Part 1. Group Identifier – Group identifiers are allocated by the international ISBN Agency in Germany. Groups are determined by national, geographic, language or other convenient group and varies in size according to the publishing output of the group.

Examples of group identifiers are:
0 United Kingdom, Canada, U.S.A., Australia, Zimbabwe etc.
3 Germany
81 India
951 Finland
955 Sri Lanka
971 Philippines
974 Thailand
9971 Singapore
99936 Bhutan

Part 2. Publisher Identifier – The publisher identifier designates the publisher of a given book. Publishers with a large output of books are assigned a longer publisher identifier.

Part 3. Title Identifier – This part identifies a particular title or edition of a title published by a particular publisher. Title identifier depend upon the length of the Publisher identifier.

Part 4. Check Digit – The “Check Digit” is the tenth and last digit in an ISBN and is computed as the result of an elaborate calculation on the other nine digits. This is a single digit at the end of the ISBN which provides an automatic check on the correctness of the ISBN

The full advantages of participation in the ISBN scheme are achieved only when the ISBN is actually printed in the publication. This means that ISBNs must be allocated before a book goes to the Printer.