- Dewey Decimal System

The Dewey Decimal Classification (DDC) system is a widely used library classification system that organizes books by assigning them a numerical code based on their subject matter. It was created by Melvil Dewey in 1876 and has been updated and revised over time. The system divides knowledge into ten main classes, each represented by a three-digit number. These main classes are further divided into subclasses and more specific topics.

Here are the ten main classes of the Dewey Decimal system:

000 - General Works
This class includes general reference works, computer science, information, and journalism.

100 - Philosophy and Psychology
This class covers topics related to philosophy, metaphysics, ethics, and various branches of psychology.

200 - Religion
This class includes books on various religions, religious texts, theology, and religious institutions.

300 - Social Sciences
This class covers topics related to sociology, economics, law, politics, and other social sciences.

400 - Language
This class includes works on linguistics, grammar, language learning, and specific languages.

500 - Natural Sciences and Mathematics
This class covers topics in the physical and natural sciences, including mathematics, astronomy, chemistry, biology, and earth sciences.

600 - Technology (Applied Sciences)
This class includes books on technology, engineering, medicine, agriculture, and other applied sciences.

700 - Arts and Recreation
This class covers the fine arts, performing arts, sports, games, and various forms of recreation.

800 - Literature
This class includes works of literature, literary criticism, and works about specific authors and their works.

900 - History and Geography
This class covers historical works, geography, travel, and biographies related to history and geography.

Each main class can be further divided into subclasses and more specific topics using additional digits after the decimal point.