Dewey Decimal Classification

"Dewey Decimal" redirects here. Not to be confused with Duodecimal.
"The Dewey Decimal System" redirects here. For the novel by Nathan Larson, see The Dewey Decimal System (novel).
A library bookshelf in Hong Kong classified using the New Classification Scheme for Chinese Libraries, an adaptation of the Dewey Classification scheme

The Dewey Decimal Classification (DDC), colloquially known as the Dewey Decimal System, is a proprietary library classification system which allows new books to be added to a library in their appropriate location based on subject.[Note 1] It was first published in the United States by Melvil Dewey in 1876.[1] Originally described in a 44-page pamphlet, it has been expanded to multiple volumes and revised through 23 major editions, the latest printed in 2011. It is also available in an abridged version suitable for smaller libraries. OCLC, a non-profit cooperative that serves libraries, currently maintains the system and licenses online access to WebDewey, a continuously updated version for catalogers.

The decimal number classification introduced the concepts of relative location and relative index. Libraries previously had given books permanent shelf locations that were related to the order of acquisition rather than topic. The classification's notation makes use of three-digit numbers for main classes, with fractional decimals allowing expansion for further detail. Numbers are flexible to the degree that they can be expanded in linear fashion to cover special aspects of general subjects.[2] A library assigns a classification number that unambiguously locates a particular volume in a position relative to other books in the library, on the basis of its subject. The number makes it possible to find any book and to return it to its proper place on the library shelves.[Note 2] The classification system is used in 200,000 libraries in at least 135 countries.[3][4]


Cite error: There are <ref group=Note> tags on this page, but the references will not show without a {{reflist|group=Note}} template (see the help page).

  1. ^ Dewey, Melvil (1876), Classification and Subject Index for Cataloguing and Arranging the Books and Pamphlets of a Library (Project Gutenberg eBook), archived from the original on November 10, 2012, retrieved July 31, 2012
  2. ^ Chapter 17 in Joudrey, Daniel N.; Taylor, Arlene G.; Miller, David P. (2015). Introduction to Cataloging and Classification (11th ed.). Santa Barbara, CA: Libraries Unlimited/ABC-CLIO. ISBN 978-1-59884-856-4.
  3. ^ "Dewey Services". OCLC. 2009. Archived from the original on January 31, 2010. Retrieved November 4, 2009. Offers library users familiarity and consistency of a time-honored classification system used in 200,000 libraries worldwide
  4. ^ "Countries with libraries that use the DDC". OCLC. 2009. Archived from the original on March 14, 2010. Retrieved November 4, 2009. Libraries in more than 135 countries use the Dewey Decimal Classification (DDC) system to organize their collections for their users. [135 countries are listed.]