The complete Dewey Decimal Classification as used in Shelvd — every main class, division, and section, with guidance for the collector who wants to understand what librarians did with their books.
A Brief History of Decimal Tyranny
In 1876, a twenty-five-year-old library assistant at Amherst College named Melvil Dewey published a pamphlet titled A Classification and Subject Index for Cataloguing and Arranging the Books and Pamphlets of a Library. His idea was elegant and, some would say, arrogantly simple: divide all human knowledge into ten classes, each class into ten divisions, each division into ten sections, and extend with decimals whenever the universe proved more complicated than anticipated.
It always did. The universe is inconsiderate that way.
Today the DDC is used by over 200,000 libraries in 135 countries. It is maintained by the Library of Congress (which, ironically, uses its own classification system instead). The current edition is the 23rd, published in 2011 — which is the edition Shelvd's 1,177 entries are drawn from.
How It Works
A DDC number has at least three digits. The first digit is the main class, the second the division, the third the section. Everything after a decimal point refines further:
823.912
│││ │││
│││ └┘┘── Period subdivision: 1900–1945
││└───── Section: English fiction
│└────── Division: English literature
└─────── Main class: Literature
The beauty of the system is that you can read a DDC number from left to right and learn progressively more about the book's subject. The horror is that some numbers have grown to twelve digits or more, at which point they tell you everything about the book except where you left it.
The Ten Main Classes
| Class | Subject | What's in it |
|---|---|---|
| 000 | Computer Science, Information & General Works | Encyclopedias, journalism, UFO studies, and — since 2011 — the entire internet |
| 100 | Philosophy & Psychology | From ancient Greeks to cognitive behavioral therapy, with stops at ethics and the paranormal |
| 200 | Religion | Every faith, every text, every denomination. Christianity gets 200–289; everyone else shares 290–299 |
| 300 | Social Sciences | Economics, law, politics, education, folklore, and the perennial mystery of how societies function |
| 400 | Language | Linguistics, grammar, dictionaries. English gets 420; the rest of the world's languages fit in 490 |
| 500 | Science | Mathematics, astronomy, physics, chemistry, biology. Pure science only — applications live in 600 |
| 600 | Technology | Medicine, engineering, agriculture, cooking, pets, and anything else humans do with science |
| 700 | Arts & Recreation | Fine arts, music, sports, games. Architecture is here. So is stamp collecting |
| 800 | Literature | Organized by language first, then form. English literature gets 820; American English is a subdivision of it |
| 900 | History & Geography | History by place, biography, and geography. Ancient history starts at 930; travel is in 910 |
Why Collectors Should Care
DDC numbers appear on the copyright page of most books published since the 1970s, as part of the Cataloging-in-Publication (CIP) data. They're also returned by most library providers during Library Lookup.
For a collector, the DDC is useful for three things:
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Finding related works — Books with similar DDC numbers are about similar subjects. If you're building a collection around a topic, DDC numbers help you discover adjacent works you might have missed.
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Understanding how your book is classified — A book you think of as "natural history" might be classed under 508 (natural history), 591 (zoology), or 639 (hunting and fishing). The DDC number reveals how the cataloging world sees your book.
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Enriching your records — When Library Lookup returns a DDC number, Shelvd resolves it to its full description. A raw "823.912" becomes "Literature → English literature → English fiction → 1900–1945" — which is considerably more informative.
In Shelvd
The DDC field lives in the Subject Classification section of the edit form. Type a number and Shelvd resolves it to its description. Or type a description — "English fiction" — and Shelvd suggests matching codes.
Shelvd contains 1,177 DDC entries from the 23rd edition (abridged). This covers all main classes, divisions, sections, and the most commonly used subdivisions. It does not contain the full unabridged schedules, which run to four printed volumes and cost more than most of the books they classify.
The Complete Table
Below are all 1,177 entries in Shelvd's DDC reference table, grouped by main class.
000 — Computer Science, Information & General Works
The class for things that don't fit anywhere else — which is either a pragmatic solution or a philosophical surrender, depending on your temperament. Encyclopedias, journalism, library science, and computing all live here. So does 001.9 (controversial knowledge), which covers UFOs, the Bermuda Triangle, and conspiracy theories — because even the Dewey system needs a junk drawer.
100 — Philosophy & Psychology
From Plato to psychoanalysis. Ethics at 170, the paranormal at 130, and logic at 160. Western philosophy dominates the structure; Eastern philosophy was retrofitted into 180–189, which tells you something about when the system was designed.
200 — Religion
Christianity occupies 200–289. Judaism, Islam, Buddhism, Hinduism, and every other world religion shares 290–299. Dewey was a product of his time. The 23rd edition has made improvements, but the structural bias remains visible.
300 — Social Sciences
The broadest class and the most politically charged. Economics (330), law (340), education (370), and social problems (360) all live here. So does folklore (398), which means fairy tales and tax policy share a main class.
400 — Language
Linguistics and grammar. Each language gets its own division: English (420), German (430), French (440), Spanish (460). The structure mirrors the 800s (Literature) — by design, so that language and literature about the same tongue share the same second digit.
500 — Science
Pure science only. Mathematics (510), astronomy (520), physics (530), chemistry (540), biology (570). If a scientist applies the knowledge — building a bridge, curing a disease — the book moves to 600.
600 — Technology
Everything practical. Medicine (610), engineering (620), agriculture (630), home economics (640), business management (650). This is where cooking lives (641.5), which means Julia Child and a manual on sewage treatment (628) are in the same main class.
700 — Arts & Recreation
Fine arts (700–770), music (780), and recreation (790). Architecture is at 720. Photography at 770. Sports at 796. The class has an admirable range: Michelangelo and miniature golf, separated by a hundred numbers.
800 — Literature
Organized by language, then by form. English literature (820), German literature (830), French literature (840). Within each language: poetry (-1), drama (-2), fiction (-3), essays (-4). American literature is a subdivision of English literature (813 = American fiction), which has caused exactly the arguments you'd expect.
900 — History & Geography
History by region: Europe (940), Asia (950), Africa (960), North America (970). Biography lives at 920 — though many libraries prefer to shelve biographies separately. Geography and travel (910) are here too, next door to ancient history (930).
The DDC table contains 1,177 entries. For the full table, see the reference data in Shelvd's database. During editing, the DDC field provides bidirectional search — type a code or a description, and Shelvd resolves the other.