The ISBN (International Standard Book Number) is a unique machine-readable identification number, which marks any book unmistakably. This number is defined in ISO Standard 2108. The number has been in use now for 30 years and has revolutionised the international book-trade. 166 countries and territories are officially ISBN members. The ISBN accompanies a publication from its production onwards.
The number consists of ten digits:
Group identifier
Publisher identifier
Title identifier
Check digit
The ISBN is divided into four parts of variable length, which must be separated clearly by hyphens or spaces:
ISBN 0 571 08989 5
or
ISBN 90-70002-34-5
The number of digits in the first three parts of the ISBN (group identifier, publisher prefix, title identifier) varies. The number of digits in the group number and in the publisher prefix is determined by the quantity of titles planned to be produced by the publisher or publisher group. Publishers or publisher groups with large title outputs are represented by fewer digits.
To get more details about the ISBN-number see the International ISBN Agency website.
What are the practical aspects of ISBN?
Forget about dealing with complicated bibliographic records - it is all identified by the 10-digit number. In order to avoid mistakes, use the bar-coded form - the ISBN is easily turned into an EAN Bookland bar-code and is processed by the usual bookstore, general store or supermarket electronic systems. Books in Print catalogues and the Publishers' International ISBN Directory keep you up-to-date on title and publishers identification.