Dewey Decimal System

If you were a librarian, how would you organize the seemingly endless number of books under your care? One of the easiest ways to do so may be to arrange them alphabetically, but is that really helpful?

Using that system, a book titled Human Biology may be next to Bob’s Big Adventure. The two books have nothing in common, and someone looking for books on human biology would have to know either the name of each book he’s looking for or blindly search each shelf to find other books on the same topic.

With that being said, a better system would be to organize books based on the topic, which is exactly what Melvil Dewey thought.

What Is the Dewey Decimal System?

American librarian Melvil Dewey invented the Dewey Decimal System (DDC) in 1873 to be used in the Amherst College Library. His system was then published in 1876 and has since been adopted by over 135 countries.

Since then, the DDC has been continually revised to keep up with new knowledge.

Dewey Decimal System Classification

The DDC uses a classification method that organizes books based on ten primary categories. This method uses a series of numbers to identify each category. The ten primary categories are:

  • 000—Computer Science, Information, and General Works
  • 100—Philosophy and Psychology
  • 200—Religion
  • 300—Social Sciences
  • 400—Language
  • 500—Science
  • 600—Technology
  • 700—Arts and Recreation
  • 800—Literature
  • 900—History and Geography

In other words, if you want to find a book within the religion category, then you will look for books between 200 and 299.

But the system is much more robust than simply searching through all the books in the 200s.

Dewey Decimal Number Lookup — Examples

Each number refers to a certain category of topics. For example, if you want to find books on ethics, then you would first go to the 100 to 199 section. Books on ethics can be found between 170 and 179:

  • 170—General
  • 171—Systems and Doctrines
  • 172—Political Ethics
  • 173—Ethics of Family Relationships
  • 174—Economic and Professional Ethics
  • 175—Ethics of Recreation and Leisure
  • 176—Ethics of Sex and Reproduction
  • 177—Ethics of Social Relations
  • 178—Ethics of Consumption
  • 179—Other Ethical Norms

Believe it or not, the system can get even deeper. A decimal point is added after the first three numbers to further distinguish between categories.

For example, if you are looking for a book on the history of the U.S. Constitution, then you would first go to the History section (900s). The History of North America is found in the 970s with the History of the United States being in the 973s.

The History of the United States is further subdivided using a decimal point. In this case, the Constitutional period is located in 973.4s. The topic can be further subdivided with many books having two to three numbers after the decimal point.

While uncommon, evolving topics often lead to a series of numbers after the decimal point. For example, books on computer lawyers can be found in the 343.0999092s section.

As the world’s knowledge continues to advance, subsections will continue to evolve as more subcategories come to light.

Do Libraries Still Use the Dewey Decimal System?

In the computer age, you may wonder if the DDS is still used today. The short answer is “yes,” with many libraries actively using the system worldwide. In fact, the system is continually maintained and updated by the Dewey editorial office located in the Library of Congress.

Editors propose revisions and expansions which are then reviewed by an international board called the “Classification Editorial Policy Committee”.

While librarians use the DDS to categorize and organize books, there’s no need to know the system by heart to find a book as many libraries often have public computers that can be used to search for books by category, author, title, and more.

There are also numerous online databases, like the ISBN database, that make searching for books a lot easier.

Librarians can also use these online databases to categorize the books under their care. Instead of manually coming up with each DDS number, librarians can look the book up using WebDewey —the electronic version of the DDS—to find the corresponding number.

This allows librarians worldwide to accurately label each book, allowing for a more unified system.

Dewey Decimal System

Final Thoughts

The Dewey Decimal System has brought a uniform and topic-based approach to categorizing books, making libraries easier to navigate. While all those numbers may be intimidating at first, the primary ten categories will help narrow down your search with each number after the first continuing to divide the topic into further subcategories.