Dewey Decimal Classification (DDC)

The Dewey Decimal Classification (DDC) is a way of organizing books in a library so that related topics are shelved together. The system identifies each book by its subject in such a way that adding a book to a grouping does not require renumbering books. It is the most widely used library-organizational system in the world and is constantly evolving as content is added.

Origins

The Dewey Decimal Classification (DDC) system was invented in 1873 by Melville Dewey (1851-1931), then a student assistant at the Amherst College library in Massachusetts. Dewey, who later became a founder of the American Library Journal and the organizer of the first conference for librarians, published his classification system in 1876.

Prior to this, a library numbered each book in its collection according to its location on the shelves. A book always had the same number in a library but not necessarily in other libraries, and books on related topics were not usually shelved together. This system made it possible for patrons to locate individual books, but they had to look up each book individually in a master file. The system also made it more difficult for patrons to find books on related subjects.

Dewey revamped this system and numbered books in relation to each other in a way that puts books of like topics together. Other libraries adopted his system, creating the first standardized means of locating books in nearly any library.

Structure of the DDC

Under the DDC, books are first grouped into general categories, or classes, and given a three-digit Arabic number based on the overall subject matter. These are the ten broad categories for classification:

• 000—is the most general and includes reference works such as encyclopedias and periodicals. It also includes computer science topics, something that did not exist when Dewey created the system.
• 100—is dedicated to works of philosophy and psychology, occultism, and parapsychology.
• 200—includes works related to religion.
• 300—includes all social sciences, such as anthropology, sociology, political science, law, economics, education, communication, and customs.
• 400—is dedicated to language, specific languages, and linguistics.
• 500—covers natural sciences and mathematic topics.
• 600—includes all technology.
• 700—is dedicated to the arts (fine and decorative arts, music, and performing arts) as well as sports and games.
• 800—is dedicated to literature and includes prose, poetry, and drama.
• 900—encompasses history and geography.

The first numeral in the three-digit number defines a book's general classification. The second numeral indicates a division of that classification, and the third further classifies the book within its division. For example, the 900 classification is for books about history and geography, while the 910 classification is for books about geography and travel. Books starting with 920 are about biography and genealogy, and books starting with 930 are about the history of the ancient world. The third number further classifies a book—a book with the number 931 is about the history of ancient China and a book with the number 932 is about ancient Egypt.

Dewey's system added decimal points to provide more refined classification. In this instance, the decimal point is more like the period in a sentence than a mathematical device; it signals a pause in reading or copying the number. The portion of the number to the right of the decimal point can have as many digits as necessary to allow for a detailed classification of the book's subject matter. For example, a book about caring for dogs is classified as 636.7, with the first "6" representing the broad class of technology, the "3" representing agriculture and related technology, the second "6" serving as the notation for animal husbandry, and the "7" after the decimal point indicating that the book is about dog care. Additional numbers after the decimal point could be added to define different facets of dog care.

Advantages and Disadvantages of the DDC

The DDC revolutionized the way patrons used a library by making it easy to locate books by their classification and find multiple books on one topic. The system also allowed for the addition of new topics and classifications. For example, books about scientific breakthroughs that did not exist when the system was designed can be added to the system because the overall categories and divisions are sufficiently broad.

While the DDC is widely used, the system has some drawbacks. One problem occurs when books span a number of categories. For example, while the 800 classification is designated for literature books, folk literature is considered a cultural custom and is actually classified within the social sciences.

Alternatives to the DDC

While the majority of public libraries and some university libraries use the DDC, the Library of Congress and most research and university libraries use the Library of Congress Classification (LCC) system. Established in 1891 specifically for the Library of Congress, the LCC divides books into twenty-one classes, each designated by a single letter. Additional letters, whole numbers, and decimals are added to create a call number that can identify and locate any unique item in the library's collection. However, because most libraries use the DDC and patrons are familiar with this system, the Library of Congress began using both the LCC and the DDC in 1930.

In the early twenty-first century, some libraries serving younger children began to experiment with classifying books by placing them alphabetically by title within a broad category. For example, the classification "Animals" includes all books about animals, whether they are about a specific animal or animal care. The classification "Animals" also includes both fiction and nonfiction (which might be denoted by a colored dot on the book's spine). Proponents of this system believe it helps young children who have not yet learned decimals to locate more books of interest.

Bibliography

"The Dewey Program at the Library of Congress." Library of Congress. Web. 11 Jan. 2016.

http://www.loc.gov/aba/dewey/

"Dewey Decimal Classification." ipl2, The iSchool at Drexel College of Information Science and Technology. 2013. Web. 11 Jan. 2016.

http://www.ipl.org/div/farq/deweyFARQ.html

"Dewey Decimal in the UIUC Bookstacks." University of Illinois at Urbana-Champaign. Web. 11 Jan. 2016.

http://www.library.illinois.edu/circ/tutorial/deweyintro.html

"Introduction to the Dewey Decimal Classification." OCLC. Online Computer Library Center. Web. 11 Jan. 2016.

http://www.oclc.org/content/dam/oclc/dewey/versions/print/intro.pdf Kaplan, Tali Balas, et. al. "Are Dewey's Days Numbered?: Libraries Nationwide are Ditching the Old Classification System. School Library Journal. 20 Sept. 2012.Web. 11 Jan. 2016.

http://www.slj.com/2012/09/collection-development/are-deweys-days-numbered-libraries-across-the-country-are-giving-the-old-classification-system-the-heave-ho-heres-one-schools-story/#‗