Dewey Decimal Classification

Dewey Decimal Classification, in library science, a method of classifying knowledge for the purpose of cataloging books and other library materials, devised by Melvil Dewey. Under this system all knowledge is divided into ten main classes, each of which is designated by a 100-number span. The first span, starting with 000, includes general works, such as encyclopedias, newspapers, and periodicals; the 100s are used for philosophy and psychology; 200s, religion; 300s, social sciences; 400s, language; 500s, natural sciences and mathematics; 600s, technology; 700s, the arts (including sports and recreations); 800s, literature and rhetoric; 900s, geography, history, biography, and travel. Each main class is divided into ten subclasses; for example, in the 800s, 810 is used for American literature, 820 for English literature, 830 for German, etc. Each of these in turn is divided; in the 810s, 811 indicates American poetry and 813 fiction. Even more specific breakdowns, to indicate geographic location, chronological period, or the form of the material, are designated by numbers after a decimal point following the third digit. For example, 813.4 is used for American fiction from 1861 to 1900, and 813.46 indicates a work by or about the novelist Henry James.

The classification scheme was originally issued by Dewey in a 42-page booklet printed in 1876; the latest of 19 revisions of his Decimal Classification and Relative Index appeared in three volumes in 1979. Although it is used in libraries throughout the world, another classification system, devised by the Library of Congress, has been adopted by many libraries as more practicable for larger and more specialized collections (see Library of Congress Classification).

For more information on Dewey Decimal Classification, see Library: Dewey Decimal Classification.