Dewey - What’s with all the numbers?

Melvil Dewey, born Dec 10, 1851, died Dec 26, 1931, was a librarian, educator, and the founder of the American Library Association. He is best known for creating the Dewey Decimal Classification. This system, in its simplest form, organizes like materials together by subject using numbers.

Ten main classes define all knowledge, from 000 to 900. Yes! Those zeroes are important.

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

Each main class is broken down into finer and finer detail by utilizing the tens, ones, and MORE numbers following a decimal point.

Here’s an example: 027 is for General Libraries, Archives, Information Centers.

Public libraries are 027.4 and public library outreach programs (including bookmobiles) is 027.42.

But Wait! There’s More.

Want to brush up on algebra? Math is in the sciences, 500. Specifically, 510-519 and algebra is 512.9. But the titles all sound and look a lot alike. Ah, there’s a letter under the number. What’s that for? It usually stands for the first letter of the author’s last name, though it could also be for the first letter of the title (ignoring a, an, and the), or some other identifier. More than one book can have the same Dewey number. Picture three different algebra books with 512.9 S; one by Sargent, one by Smith, and one by Stewart.

Non-Fiction titles use the Dewey Decimal Classification to organize topics sequentially by number and letter and does its best to keep similar subjects together. Yet, Melvil Dewey also built his system to be flexible. Teams of professionals strive to keep the DDC updated.

Still confused? Ask a Librarian!  Or go to 641.8654 and make yourself some cookies.

This post was written by Mary Vander Linde, Adult Services Librarian.