Introduction to Dewey Decimal Classification

What is the Dewey Decimal Classification

To classify means to identify and group items into classes by organizing knowledge according to common characteristics, for example by subject. In library science, classification is used to associate the conceptual content of a book (or document) with its physical shelf location.

The most widely used bibliographic classification system in the world is the Dewey Decimal Classification (DDC), invented in 1873 by the American librarian Melvil Dewey. It is a tool that has been constantly revised so as to be updated to all new knowledge acquisitions. In fact, the DDC has reached its 23rd edition.

Read our tips on how to find your way around the shelves.

On the topic:

Associazione Italiana Biblioteche. Introduzione alla Classificazione Decimale Dewey - AIB WEB.
Chan Lois Mai and Joan S Mitchell. Dewey Decimal Classification : Principles and Application. 3rd ed. Dublin (Ohio): OCLC, 2003.

Organization and functionality

What the DDC consists of

The Dewey Decimal Classification scheme (organized hierarchically) groups knowledge into 10 macro-classes, each of which is divided into 10 divisions and each division into 10 sections. This system allows new classes to be added or existing classes to be expanded unlimitedly by inserting new topics.

The 10 macro-classes are:

000 Computer, information and general works
100 Philosophy and psychology
200 Religion
300 Social sciences
400 Language
500 Pure science
600 Technology
700 Arts and recreation
800 Literature
900 History and geography

The main functions of the DDC

Catalographic: assigns catalogued resources to the class which correspond to the subject covered;
Topographic: allows volumes to be sorted by subject area. This means that books with the same topic are on the same shelf, thus facilitating user search.

Social and Political Science area