Identification and classification

During the 20th century, librarians were concerned about keeping track of the many books being added yearly to the Gutenberg Galaxy. Through a global society called the International Federation of Library Associations and Institutions (IFLA), they devised a series of tools including the International Standard Bibliographic Description (ISBD).

ISBN with barcode

Each book is specified by an International Standard Book Number, or ISBN, which is unique to every edition of every book produced by participating publishers, world wide. It is managed by the ISBN Society. An ISBN has four parts: the first part is the country code, the second the publisher code, and the third the title code. The last part is a check digit, and can take values from 0–9 and X (10). The EANBarcodes numbers for books are derived from the ISBN by prefixing 978, for Bookland, and calculating a new check digit.

Commercial publishers in industrialized countries generally assign ISBNs to their books, so buyers may presume that the ISBN is part of a total international system, with no exceptions. However, many government publishers, in industrial as well as developing countries, do not participate fully in the ISBN system, and publish books which do not have ISBNs.

A large or public collection requires a catalogue. Codes called "call numbers" relate the books to the catalogue, and determine their locations on the shelves. Call numbers are based on a Library classification system. The call number is placed on the spine of the book, normally a short distance before the bottom, and inside.

Institutional or national standards, such as ANSI/NISO Z39.41 - 1997, establish the correct way to place information (such as the title, or the name of the author) on book spines, and on "shelvable" book-like objects, such as containers for DVDs, video tapes and software.

Books on library shelves with bookends, and call numbers visible on the spines

One of the earliest and most widely known systems of cataloguing books is the Dewey Decimal System. Another widely known system is the Library of Congress Classification system. Both systems are biased towards subjects which were well represented in US libraries when they were developed, and hence have problems handling new subjects, such as computing, or subjects relating to other cultures.^{[ citation needed ]}

Information about books and authors can be stored in databases like online general-interest book databases.

Metadata about a book may include its ISBN or other classification number (see above), the names of contributors (author, editor, illustrator) and publisher, its date and size, and the language of the text.