The Dewey Decimal Classification (DDC) system is a general knowledge organization tool that is continuously revised to keep pace with knowledge. It is published by OCLC Online Computer Library Center, Inc. OCLC owns all copyright rights in the Dewey Decimal Classification, and licenses the system for a variety of uses.
The DDC is the most widely used classification system in the world. It is built on sound principles that make it ideal as a general knowledge organization tool: meaningful notation in universally recognized Arabic numerals, well-defined categories, well-developed hierarchies, and a rich network of relationships among topics.
The DDC organizes knowledge by disciplines or fields of study. At the broadest level, the DDC is divided into ten main classes, which together cover the entire world of knowledge. Each main class is further divided into ten divisions, and each division into ten sections (not all the numbers for the divisions and sections have been used).
The main structure of the DDC is presented in three summaries (outlines) of the Dewey Decimal Classification. The summaries give Dewey numbers and their accompanying captions. The captions have been edited to make browsing easier, and so may not match the complete heading found in the DDC classification schedules.