The basic plan of the Dewey Decimal Classification (DDC) system is a hierarchical structure that is based on a decimal numbering system. The system is divided into 10 main classes, which are arranged according to subject matter. Each main class is further divided into subclasses and categories, and each subclass and category is further divided into more specific subcategories and sub-subcategories.
The main classes of the DDC system are:
- Philosophy and psychology
- Social sciences
- Pure science
- Arts and recreation
- History and geography
Each main class is assigned a unique decimal number, and the subclasses and categories within each main class are assigned decimal numbers that are based on the main class number. For example, the subclass “Mathematics” within the main class “Pure science” (class 5) is represented by the decimal number “510,” while the category “Trigonometry” within that subclass is represented by the decimal number “517.”
In addition to the decimal numbering system, the DDC system also includes a system of captions and notation schedules that provide more detailed information about the meaning and content of each class, category, and subcategory. These tools are used in conjunction with the decimal numbering system to create a comprehensive and detailed classification system that is used to organize and classify books and other materials according to subject matter in libraries.