The Dewey Decimal Classification (DDC) system is based on a decimal numbering system, in which each class, category, and subcategory is assigned a unique decimal number. The system is hierarchical, with 10 main classes at the top and more specific categories and subcategories below them. The main classes are arranged according to subject matter, and each subclass and category is further divided and refined according to specific topics or themes.
The DDC system is an artificial classification system, which means that it is not based on the inherent characteristics or traits of the materials being classified, but rather on criteria that have been chosen by the person or group creating the classification system. In the case of the DDC, the criteria for classification are based on subject matter, and the system is designed to be flexible and adaptable so that it can be used to classify a wide range of materials.
The DDC system is widely used in libraries around the world to organize and classify books and other materials according to subject matter, and it is considered to be an essential tool for organizing and accessing information in libraries.