Dewey Decimal Classification Tools

Updated February 21, 2017

In 1873, Melvil Dewey created the Dewey Decimal Classification System. Also called the DDC system and the Dewey Decimal System, it allows libraries to organise their books on shelves in a way that makes it easy for them to be found. Over 200,000 libraries in more than 135 countries use the system.

History of the Dewey Decimal Classification System

Since Melvil Dewey's creation of the DDC system in the 1870s, it has been constantly revised. The DDC system has been through 22 unabridged print editions and 14 abridged editions since it was first published in 1876. In 1988, the Online Computer Library Center, Inc. (OCLC) took ownership of the DDC and has made it into the world's most widely used library classification system. The print edition of DDC 22 (the latest edition) was published in July 2003. The electronic version of DDC 22, the first online edition, also became available that year.

Overview of the DDC System

The Dewey Decimal Classification system is made up of 10 classes. Each class has 10 divisions, with each of those having 10 sections. The numbers range from 000.000 to 999.999. Not every number in every section is used; some haven't been allocated yet, and others have been abandoned over time. When two books have the same DDC system number, the second line consists of letters, typically the first few letters of the author's last name. Books are shelved in increasing numerical order first and then in alphabetical order, according to the second line.

Main Classes of the DDC System

These are the 10 main classes of the DDC system:

000 Computer Science, Information & General Works

100 Philosophy & Psychology

200 Religion

300 Social Sciences

400 Language

500 Science

600 Technology

700 Arts & Recreation

800 Literature

900 History & Geography

Fiction in the DDC System

While the DDC system is considered mainly to be used for nonfiction books, American fiction, for example, is technically classified at 813 under the Literature class. But since that one number could potentially take up the majority of a library's books, most libraries opt to keep the fiction and nonfiction books separate. Instead of using DDC system numbers, library patrons search for fiction books by the alphabetical order of the author's last name.

How Books Are Assigned a DDC System Number

The OCLC acquired all trademark and copyrights associated with the DDC system in 1988. Work done by the OCLC editorial staff is reviewed by the Decimal Classification Editorial Policy Committee (EPC), a 10-member international board.

Each newly published book is assigned a DDC system number by a division of the Library of Congress. The number selection is then either accepted or rejected by the OCLC advisory board. Almost 100 per cent of the recommended numbers are accepted.

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About the Author

Toby Welch has been a full-time freelance writer since 2003. She has published in the "National Post," "Cottage," "Opulence," "Alberta Parent," "The Real Estate Magazine" and Living Safety," as well as many more articles online. Toby holds an accounting degree from the University of Calgary.