Dewey Decimal System: Definition, History & Example

Instructor: Natalie Klema

I have been a high school math instructor for 10 years. I have a Master's degree in Leadership.

This lesson will explain the Dewey Decimal System. The Dewey Decimal System is used to categorize books by subject to make placing new books or locating existing books in the library possible. It is essential to understand how the books are numbered to be able to use the library effectively.

The Dewey Decimal System

The Dewey Decimal System was first published in 1876 by a librarian named Melvil Dewey. Dewey created library science, and is considered the 'Father of Modern Librarianship.' It is a system that numbers books based on their subject. This system is used in 200,000 libraries in at least 135 countries. It allows the books to be organized on the library shelves in a way that makes it easy for readers to find the book they want.

Before the Dewey Decimal System was created, the placement of books was arbitrary. Individual librarians simply placed them how they wanted. Some libraries simply arranged books on the shelf so they looked nice. No attention was paid to what the book was or what it contained. This was called the fixed location approach. A catalog was made telling on what shelf the book was kept. This made it difficult to add new books because that might mean moving others. Then, the catalog would have to be updated for each new book. Other libraries arranged the books in alphabetical order with no regard to their content.

How the Dewey Decimal System Works

In the Dewey Decimal System, books are categorized based on their subject matter. Books with similar subjects are then arranged together on library bookshelves to make locating desired materials easier. All the books on a topic are kept together. There are ten main classes of topics in the system. These are the main classes:

000 - Generalities, Computer Science, and Information

100 - Philosophy and Psychology

200 - Religion

300 - Social Sciences (anthropology, archeology, sociology)

400 - Language

500 - Natural Sciences (biology, astronomy, etc.) and Mathematics

600 - Technology (applied sciences)

700 - The Arts

800 - Literature and Rhetoric

900 - Geography and History

Each of the ten main categories has 99 divisions, which are more specific categories that fall under the main category. These are used to more accurately classify a book.

How the Dewey Decimal System Numbers Work

Books are given call numbers based on what the book is about. The first number is the main class. Each number after the first describes a subclass within the main class. For example, the number 636.7 relates to the topic in this way. The first 6 refers to Technology (Applied Science). The 3 is for Agriculture. The second 6 represents Animal Husbandry. And, the 7 is for dogs. So, any book about dogs will have the number 636.7.

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