The
Dewey Decimal
Classification(DDC), is devised by Melvil
Dewey in 1876, is a method
of classifying and cataloging library materials by subject.
Introduction
The DDC is the most widely used classification system in the world. It is adopted by Libraries in more than 135 countries. The DDC has been translated into over thirty languages.
Structure and Notation
The DDC is a general knowledge organization tool. In DDC, basic classes are organized by subjects. DDC is divided into ten main classes, each main class is further divided into ten divisions, and each division into ten sections. The more numbers, the more specific the subject. In this way, the Dewey classification system progresses from the general to the specific. For a detailed summary for each number please see Dewey Decimal System. There are three summaries( or layers):
The first summary contains the ten main classes. The first digit in each
three-digit number represents the main class. For example, 300 represents
Social Science.
The second summary contains the hundred divisions. The second digit in each three-digit number indicates the division. For example, 900 is used for Geography and History, 970 for General history of North America.
The third summary contains the thousand sections. The third digit in each
three-digit number indicates the section. Thus, 900 is used
for Geography and History, 970 for General history of North America. 973 is
used for United States.
Arabic numerals are used to represent each class in the DDC. A decimal point follows the third digit in a class number, after which division by ten continues to the specific degree of classification needed.
A subject may appear in more than one discipline. For example, “clothing” has aspects that fall under several disciplines. The psychological influence of clothing belongs in 155.95 as part of the discipline of psychology; customs associated with clothing belong in 391 as part of the discipline of customs; and clothing in the sense of fashion design belongs in 746.92 as part of the discipline of the arts.
Hierarchy
Hierarchy in the DDC is expressed through structure and notation. Structural hierarchy means that all topics (aside from the ten main classes) are part of all the broader topics above them. The italicized digits in the following example demonstrate this hierarchy:
300 Social science
340 Law
346 Private law
"Private law" and "Law" are more specific than "Social science"; they are equally specific as each other; and" " is less specific than ""
