A Guide to Library Books: The Dewey Decimal System

Updated February 21, 2017 | Factmonster Staff

Imagine walking into a house where room after room is filled with shelves, all packed with books in no specific order. Imagine trying to find the one book you want! That's what happened every day to Melvil Dewey, an American librarian who lived from 1851 to 1931. He became so unhappy trying to help people find books that he invented the Dewey Decimal System of Classification, which is still used in libraries today. The system numbers books by their subject matter in the following way.

Dewey Decimal System

000-099 General Works (encyclopedias, magazines, almanacs)
100-199 Philosophy and Psychology
200-299 Religion and Mythology
300-399 Social Science
400-499 Language
500-599 Math and Science
600-699 Medicine and Technology
700-799 Arts and Entertainment
800-899 Literature
900-999 History and Geography
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