A Guide to the Dewey Decimal System

By The Cumudgeony Librarian

In today’s library finding books that you want to read is tricky, but not impossible. Back in the old days the library looked nothing like it does now. Back then books were in what were called “closed stacks.” This meant that the books were behind a counter and the library users-or patrons-had to ask the library staff to go and fetch all the books they wanted to see. This was time consuming and hard for both staff and patrons. After all, the patrons would have to know exactly which books they were looking for, not to mention the loss of privacy in having to share with the librarian what you were interested in reading.

Then in the 1860s there was an explosion in the number of libraries in the United States. Libraries began to spring up everywhere. People flocked to the library in never before seen numbers. The Librarians were overjoyed at this sudden growth, but face with a problem of not enough staff to get the books quickly enough for all these new patrons. Libraries decided to change over to something called “Open Stacks” to help all the new patrons. The patrons could browse the stacks looking and searching themselves.

But there was a problem, before open stacks the books were organized by something called “shelf order.” This meant that the books were organized by when they came in, so a book on cats could be stuck right next to one on mathematics and another on the biography of John Stuart Mill. This would be confusing to patrons and take up more of their time. This was a Bad Thing. One of our most basic rules is “whenever possible save the time of the patron.”

This being the case, shelf order had to go. Some parts of fixing this problem were easy. Fiction books could be shelved alphabetically by author’s last name. Biographies could be shelved alphabetically by the subject’s name as well.

As nice as this was, it still left the sticky problem of the non-fiction collection. How does one organize non-fiction so that people don’t have to spend hours looking for titles?

Many librarians had wrestled with this problem, but in 1876 Melvil Dewey, an early library pioneer came up with a system for classifying books and other materials by subject matter. Dewey’s work built on the past work such as Charles A.Cutter, but the key point of Dewey’s work was that it was flexible. First published in the late 19th century, it is still in use and has been revised many times. Currently it is in its 22nd revision with the publication of the "http://www.oclc.org/dewey/versions/ddc22print/default.htm" target="_blank">DDC 22 in
July of 2003.

While the most commonly used system in US public libraries, Dewey’s Decimal system isn’t the only system out there. The Library of Congress Classification(LCC) is used in most research and university libraries. The Universal Decimal Classification (UDC) is an elaboration of the Dewey system and is used in specialized libraries such as music libraries or document archives. The Colon Classification (CC) has proved particularly popular in India and in many parts of the world.

So, how does the Dewey System work? The Decimal System is based on the number ten. Subjects are divided into ten main groups that are represented by a series of numbers: from 000 to 900.

Each of these ten groups of 000 to 900 is then further divided down into more specialized subject fields, again represented numerically, for example:

For more information there is also an Alphabetical Guide to Common Subject Headings, which has dewey numbers for the more commonly used subjects.

The Dewey Decimal Classification is © 1996-2003 OCLC Online Computer Library Center, Inc.
DDC, Dewey, and Dewey Decimal Classification are registered trademarks of OCLC Online Computer Library Center, Inc.

All copyright rights in the Dewey Decimal Classification system are owned by OCLC.
Dewey, Dewey Decimal Classification, DDC, OCLC and WebDewey are registered trademarks of OCLC.

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