Very simply, the DDC is an organizational tool that makes it easy for you to find the books and other materials you want. This system got its name from Melvil Dewey (1851-1931), who introduced his great idea for organizing library collections in 1876. Using numbers, he categorized or classified information into main classes, divisions, sections, and even smaller parts, so that each library item could be assigned a classification number that best indicated its main subject matter. This provides a way of keeping all the items on the same subject in the same area on the shelves. The DDC has lots of subjects— thousands of them! (To see a summary of all 1,000 numbers spelled out, click here)
a) Main Classes
The DDC divides subjects into ten main classes, like this:
000 Computer Science, Information & 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
b) Divisions
These ten main classes are each divided into ten divisions. Here’s an example using the 200 Religion class (based on the 22nd edition of the DDC published in 2003):
Main class:
200 Religion
Division:
210 Philosophy and Theory of Religion
220 The Bible
230 Christianity and Christian Theology
240 Christian Practice and Observance
250 Christian Pastoral Practice and Religious Orders
260 Christian Organization, Social Work and Worship
270 History of Christianity
280 Christian Denominations
290 Other Religions
c) Sections
Each of these divisions is further subdivided into ten sections. Using the 220 Bible division as an example:
Main class:
200 Religion
Division:
220 The Bible
Section:
221 Old Testament (Tanakh)
222 Historical Books of Old Testament
223 Poetic Books of Old Testament
224 Prophetic Books of Old Testament
225 New Testament
226 Gospels and Acts
227 Epistles
228 Revelation (Apocalypse)
229 Apocrypha and Pseudepigrapha
d) Decimal Numbers
In a classification number, main classes, divisions and sections are always on the LEFT side of the decimal point. But what about the numbers on the RIGHT side of the decimal point? The numbers on the right side are used to divide a specific subject into even MORE specific parts of a subject.
For example, a book on the Anglican Church in the State of Perak in Peninsular Malaysia would be classified as 283.595114. Note how, as we analyze the call number, each line leads to more specific information about the book's subject:
200 Religion (Main class)
280 Christian Denominations (Division)
283 Anglican Church (Section)
283.5 Anglican Church in Asia (Decimal numbers)
283.57 Anglican Church in Southeast Asia
283.575 Anglican Church in Malaysia
283.5751 Anglican Church in Peninsular Malaysia
283.575114 Anglican Church in Perak
Are you confused yet? It’s just like sorting your clothes by type and colour, or your music by the kind of genre and the performer.