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The Dewey Decimal Classification System

The Dewey Decimal Classification (DDC) system helps to organize (classify) non-fiction books in the library by organizing information into 10 categories, which are called "classes". You can organize books generally into these 10 main classes, or you can organize information more specifically depending on how detailed the book's subject is. When you sort information categorically under the 10 main classes, it is called a "hierarchy". The DDC displays this hierarchy of information using numbers.

The 10 Classes
000 Computer science, information & general works
100 Philosophy & psychology
200 Religion
300 Social sciences
400 Language
500 Science
600 Technology
700 Arts & recreation
800 Literature
900 History & geography

How did Melvil Dewey come up with his classification system? (The following summary is based on the one used by the Children's Museum of Brooklyn website.)

 Dewey Decimal Call Number  Books About  What Question Do These Books Answer?  Example Title and Dewey Decimal Call Number
 Computer science, information &  general works  How do we organize information?
 Guinness Book of World Records (031.02 GUI)
 100~199  Philosophy & psychology  Who am I?
 How Do I Feel About: Making Friends (158.2 LEV)
 Religion  How did we get here?
 The Story of Religion (291 MAE)
 300~399  Social sciences  Who are the people in the world?
 Police Officers (363.2 REA)
 400~499  Language  How can I communicate with others?
 Sign Language for Kids (419 HEL)
 500~599  Science (and math)
 How can I explain the world around me?
 The Science of Sound and Music (534 LEV)
 600~699  Technology (applied sciences)
 How can I control the world around me?
 Everyday Machines: Amazing Devices We Take for Granted (621.8 KEL)
 700~799  Arts & recreation  How can I enjoy my free time?
 I See the Rhythm (780.899 IGU)
 800~899  Literature  What are the stories of our lives?
 Rainbow Soup: Adventures in Poetry (808.1 CLE)
 900~999  History & geography  What was the world like in the past?
 The DK Visual Dictionary of the 20th Century ( 909.802 ADA)

Each of the 10 classes can be further divided into 10 divisions (100 divisions total), and each division can be divided into 10 sections (1000 sections total). Click here to see the classes, divisions, and sections, and how the hierarchy of information looks.

So, what does this mean to you? When you're looking for a book in the library, or when the OPAC computer gives you a call number, where do you go? For example, animals are a very popular topic at the Robinson Library. Let's break down the Science class (the 500s) to the 590 division and see how Animals are classified:

500 -- Science
590 -- Animals (Zoology)
591 -- Specific topics in natural history of animals
592 -- Invertebrates
593 -- Miscellaneous marine and seashore invertebrates
594 -- Mollusks and mollusk-like animals
595 -- Arthropods
596 -- Chordates
597 -- Cold-blooded vertebrates; Fishes
598 -- Birds
599 -- Mammals
599.1 -- General topics in natural history of mammals
599.2 -- Marsupials and Monotremes
599.3 -- Miscellaneous orders of placental mammals
599.4 -- Bats
599.5 -- Cetaceans and sea cows
599.6 -- Ungulates
599.7 -- Carnivores; Land carnivores
599.8 -- Primates
599.9 -- Hominids; Humans

If a student is looking for a book about koalas, the Dewey Decimal number breaks down like this:
500 -- Science
590 -- Animals (Zoology)
599 -- Mammals
599.2 -- Marsupials and Monotremes
599.25 -- Koalas

Subpages (1): Dewey Decimal Classes