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 |
