Dewey decimal system

Dewey decimal system, devised by Melvil Dewey (1851–1931) for classification of books in libraries, based on the decimal system of numbers. Dewey divided knowledge into 10 main areas, each of these into 10 subdivisions, and so on. Thus a book could fall into one of a thousand categories, from 000 to 999. Extensions of this system added further classificatory numbers after the decimal point.

See also: Dewey, Melvil.