Library/Science/Classification/Dewey

• Dewey Decimal Classification

  • Overview

    • The Dewey Decimal Classification (DDC) is a decimal, hierarchical library classification: ten main classes, subdivided with dot notation so longer strings mean narrower subjects [1].
    • Maintained under OCLC; widely used in public, K–12, and many small academic libraries because a single integral number sorts cleanly on the shelf.

  • Context

    • First published 1876 by Melvil Dewey; revised across many editions with relocations (notably in science and computing) as disciplines evolve.
    • Contrasts with Library/Science/Classification/Library of Congress, which is letter-led and organized as separate class schedules tied to the Library of Congress print corpus.

  • Key principles

    • Ten classes (000–900) at the top level; further digits express narrower facets within each class.
    • Relative Index — Alphabetical index from natural-language terms to table numbers.
    • Standard subdivisions — Recurring patterns (history, geographic treatment, etc.) reused where the schedule allows.

  • Mechanism

    • Build a class number from the schedules (and optional auxiliary tables for area, period, language); append book number or local cutter so each item has a unique shelf string.

  • Examples

    • 500 natural sciences; 630 agriculture; computer-related classes illustrate how discipline drift is absorbed through edition updates rather than ad hoc local patches.

  • Misconceptions

    • “Dewey stops at three digits” — False; practical call numbers are often much longer for specificity.
    • “Decimal means the schedule is about arithmetic” — Wrong sense; decimal names the notation, not the subject matter.

  • Footnotes

    • [1] https://www.oclc.org/en/dewey.html