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Dewey Decimal Classification (DDC)

The Dewey Decimal Classification (DDC) scheme was devised by Melvil Dewey (1851-1931) in 1876. Since then it has been modified and expanded in the course of many revisions. DDC has been owned by OCLC since 1988.

The revision process is controlled by the Editorial Policy Committee; UK input to the revision process is through the CILIP DDC Committee (previously by the LA DDC Committee).

DDC is a hierarchical system of classifying subjects that uses decimal numbers for its categories. At each level a number can have up to ten subdivisions. Classification numbers have three or more digits; where they have more than three digits, the third and fourth digits are separated by a decimal point.

The main classes are:

  • 000 Computers, information and general reference
  • 100 Philosophy and psychology
  • 200 Religion
  • 300 Social sciences
  • 400 Language
  • 500 Science and mathematics
  • 600 Technology
  • 700 Arts and recreation
  • 800 Literature
  • 900 History and geography

It also uses faceted classification techniques, combining elements from different sections to construct numbers reflecting more complex terms. Thus two subjects can be linked, and geographical and temporal elements and / or form of item can be added to a subject.

DDC can be applied to any work, whether fiction or non-fiction. If DDC rules for fiction are followed, these items would have number from class 800. However, the size of fiction collections in libraries means they are usually shelved separately from non-fiction in A-Z author sequences and / or genre sections.

DDC still shows a bias in certain areas due to its 19th century American origins. For example, Northern Africa is allocated 961-965 but the rest of the African continent has only 966-969. Christianity has 220-289, while all other religions have only 292-299 between them; recent versions permit another religion to be placed in 220-289, with Christianity relegated to 292-289.


400 Language
420 English and Old English
423 English dictionaries

780 Music
788 Wind instruments
788.3 Flute family
788.5 Double reed instruments
788.6 Single reed instruments

330 Economy
330.94 European economy (using place element 94 for Europe)

973 United States
973.005 Periodicals concerning the United States (using form division for periodicals)

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Content by: Ann Chapman of UKOLN.
Page last revised on: 24-May-2005
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