Dewey Decimal Classification
The Dewey Decimal Classification (DDC) is a proprietary system for organizing library collections by subject, developed by American librarian Melvil Dewey and first published in 1876.[1] It employs a hierarchical structure of Arabic numerals from 000 to 999 to divide all knowledge into ten main classes—such as 000 for computer science, information, and general works; 200 for religion; and 500 for science—with decimal extensions enabling precise subdivisions for specific topics.[1] This notation-based approach facilitates the arrangement of materials on shelves by discipline, allowing related items to be grouped together while accommodating synthesis through auxiliary tables for geographic areas, languages, and standard subdivisions.[2][1] Conceived in 1873 amid efforts to standardize library practices, the DDC has evolved through continuous revisions managed by OCLC since 1988, with annual updates via WebDewey and a 2025 print-on-demand edition reflecting contemporary knowledge expansions.[1][3] As the world's most widely adopted classification scheme, particularly in public and school libraries, it supports efficient resource discovery across diverse collections and languages, though its fixed decimal framework limits radical restructuring.[2] The system's defining achievement lies in its simplicity and scalability, enabling non-specialist staff to assign call numbers, but it has faced criticism for Western-centric biases, such as disproportionate space allocated to European history and Protestant Christianity over non-Western traditions, stemming from Dewey's 19th-century worldview and persisting despite editorial efforts to broaden coverage.[4][5]History
Origins and Early Development (1873–1885)
Melvil Dewey, born in 1851, conceived the Dewey Decimal Classification (DDC) system in 1873 while employed as a student assistant in the library at Amherst College in Massachusetts.[1] As acting librarian following his graduation in 1874, Dewey sought to organize the college's collection of approximately 12,000 volumes using a hierarchical decimal notation that divided knowledge into ten main classes, each subdivided decimally for specificity.[6] This approach drew inspiration from earlier systems but emphasized mnemonic, expandable notation to facilitate cataloging and retrieval efficiency in small libraries.[7] The system's first edition appeared in 1876 as an anonymous 42-page pamphlet titled Classification and Subject Index for Cataloguing and Arranging the Books and Pamphlets of a Library, printed locally in Amherst as a proof edition to solicit feedback from the college community.[6] Dewey promptly applied the classification to the Amherst library holdings, demonstrating its practicality for arranging nonfiction materials by subject rather than size or accession order, a common prior practice.[7] To support dissemination, Dewey established the Library Bureau in 1876 as a venture to provide printed cards, supplies, and guidance for implementing the DDC, marking an early effort to commercialize library organization tools.[8] By 1885, refinements based on user input culminated in the second edition, published under Dewey's name for the first time and distributed through the Library Bureau, which expanded to include charging systems and furniture alongside classification aids.[7][6] This version extended the tables and index to 150 pages, incorporating adjustments to class boundaries and notation for broader applicability beyond academic settings.[9] The period solidified the DDC's foundational principles of relative location and synthesizable numbers, laying groundwork for its adoption in public and institutional libraries.[10]Widespread Adoption and Refinement (1885–1942)
The second edition of the Dewey Decimal Classification, published in 1885 under Melvil Dewey's name as Decimal Classification and Relativ Index for Arranging, Cataloging, and Indexing Public and Private Libraries and for Bibliographic and Bibliothecal Use, introduced the "integrity of numbers" policy, which prohibited altering existing class numbers to accommodate expansions, thereby minimizing disruptions to established library collections.[11] This edition expanded the schedules and relative index, facilitating greater adaptability while preserving stability for users. Dewey's promotion through the American Library Association (ALA), founded in 1876, and his Library Bureau, established in 1881 to supply library equipment and promote standardized practices, accelerated adoption among U.S. academic and public libraries. By the early 1890s, the system had gained traction in institutions such as Columbia University and various state libraries influenced by Dewey's role as New York State Librarian from 1889.[7] Subsequent editions refined the structure through incremental additions rather than overhauls, with the third edition in 1888, fourth in 1891, and fifth in 1894 further detailing subclasses for emerging subjects like electricity and psychology.[9] The sixth edition (1915) and seventh (1911, with Forest Press imprint from 1911) incorporated feedback from practitioners, enhancing the relative index's utility for subject access.[7] Adoption expanded internationally, particularly in English-speaking countries, as the system's decimal notation allowed for easy subdivision and mnemonic aids aided memorization. By 1920, thousands of libraries worldwide employed it, supported by Dewey's editorial oversight until his death in 1931.[11] The ALA's Decimal Classification Advisory Committee, formed in 1916, began systematizing revisions, while the 1927 relocation of the editorial office to the Library of Congress marked institutional deepening.[7] Post-Dewey, refinements continued under committees, culminating in the fourteenth edition in 1942, which added numbers for wartime technologies and social sciences without violating number integrity.[11] The Library of Congress's practice from 1930 of printing DDC numbers on catalog cards standardized application across U.S. libraries, contributing to its de facto status as the dominant classification scheme by mid-century.[7] This period's emphasis on practical expansion over theoretical redesign ensured compatibility with growing collections, though critics noted challenges in accommodating rapid knowledge growth without more flexible faceting, a limitation addressed in later eras.[11]Post-War Evolution and Institutionalization (1942–Present)
The 14th edition of the Dewey Decimal Classification (DDC), published in 1942, featured an extensive relative index exceeding 1,900 pages across two volumes, reflecting accumulated refinements amid wartime constraints on publishing.[12] Post-war recovery enabled the release of the 15th edition in 1951, designated as the "Standard Edition" for libraries with collections up to 200,000 volumes, incorporating updates to accommodate expanding knowledge in sciences and social disciplines while maintaining hierarchical stability.[12] In 1953, the Dewey Decimal Classification Editorial Policy Committee was reconstituted under joint oversight from the American Library Association (ALA), Forest Press, and the Library of Congress, establishing formalized editorial processes to ensure consistency and responsiveness to emerging fields like computing and postwar geopolitics.[7] The 16th edition in 1958 marked the first produced under this agreement, introducing structural enhancements such as refined auxiliary tables for geographic and temporal facets.[7] Subsequent editions—17th (1965), 18th (1971), 19th (1979), and 20th (1989)—progressively addressed biases in earlier classifications, expanded coverage for non-Western literatures, and integrated feedback from international users, with the 18th edition notably emphasizing relative index improvements for interdisciplinary topics.[13][7] Institutionalization advanced through Forest Press's role as steward of DDC rights, transferred from the Lake Placid Education Foundation, culminating in OCLC's acquisition of Forest Press in 1988, which integrated the system into a nonprofit cooperative serving over 200,000 libraries worldwide by the 1990s.[14] This shift enabled digital evolution, starting with Electronic Dewey in 1993—the first electronic classification tool—followed by Dewey for Windows in 1996 alongside the 21st print edition, which synchronized updates across formats for real-time access.[7] WebDewey launched in 2000, providing online subscription-based browsing and search, while Abridged WebDewey targeted smaller libraries; by 2002, these tools supported faceted navigation and user-contributed notes.[7] Later editions, including the 22nd (2003) and 23rd (2011), incorporated semantic expansions for digital media, biotechnology, and globalized scholarship, with WebDewey 2.0 in 2011 enhancing multilingual interfaces.[7] International adaptations proliferated, such as German (2005), Italian (2009), French (2015), and Spanish (2017) editions of recent versions, alongside user groups like the European DDC Users Group (2007), fostering localized refinements without altering core notation.[7] In 2018, OCLC introduced print-on-demand for editions, reducing inventory costs, and by 2024, released Dewey linked data for semantic web integration, linking classes to ontologies like Wikidata for enhanced discoverability in automated systems.[7] These developments solidified DDC's institutional framework under OCLC, prioritizing empirical updates driven by usage data over ideological revisions.[7]System Design
Hierarchical Structure and Main Classes
The Dewey Decimal Classification (DDC) employs a hierarchical structure that organizes knowledge from broad disciplines to increasingly specific topics, enabling systematic arrangement in libraries. This hierarchy is conveyed through both structural relationships, where subordinate topics are integral to all encompassing broader classes above them, and notational length, with longer decimal expansions indicating greater specificity.[15][1] The system's decimal base facilitates unlimited subdivision: each main class spans 100 numbers (e.g., 500–599), further divided into 10 divisions of 10 numbers each (e.g., 510–519 for mathematics), and then into sections (e.g., 510.1 for philosophy of mathematics), with decimal points allowing extensions like 510.92 for individual mathematicians.[15] This design, originating in Melvil Dewey's 1876 prototype, prioritizes mnemonic aids and synthesis over rigid enumeration, though it assumes a comprehensive relative index for cross-referencing multidisciplinary works.[11] At its apex, the DDC partitions the universe of knowledge into ten main classes, numbered in increments of 100 from 000 to 900, each encompassing a primary field of study or intellectual endeavor.[16] These classes reflect Dewey's 19th-century worldview, emphasizing practical utility and Western intellectual traditions, with minimal alterations to the core framework across editions despite expansions in subordinate areas.[11] The classes are as follows:| Class | Range | Discipline |
|---|---|---|
| 000 | 000–099 | Computer science, information, and general works, including encyclopedias, journalism, and library science[16] |
| 100 | 100–199 | Philosophy and psychology, covering logic, ethics, and mental processes[16] |
| 200 | 200–299 | Religion, spanning theology, comparative faiths, and sacred texts[16] |
| 300 | 300–399 | Social sciences, such as economics, law, education, and political science[16] |
| 400 | 400–499 | Language, including linguistics, specific languages, and etymology[16] |
| 500 | 500–599 | Science, encompassing natural sciences like mathematics, astronomy, biology, and earth sciences[16] |
| 600 | 600–699 | Technology, focusing on applied fields such as medicine, engineering, agriculture, and management[16] |
| 700 | 700–799 | Arts and recreation, including visual arts, performing arts, architecture, and sports[16] |
| 800 | 800–899 | Literature, by language and form, such as poetry, drama, and fiction[16] |
| 900 | 900–999 | History and geography, covering biographies, travel, and regional histories[16] |