Dewey Decimal Classification

Also called  Dewey Decimal System,   system for organizing the contents of a library based on the division of all knowledge into 10 groups, with each group assigned 100 numbers. The 10 main groups are: 000–099, general works; 100–199, philosophy and psychology; 200–299, religion; 300–399, social sciences; 400–499, language; 500–599, natural sciences and mathematics; 600–699, technology; 700–799, the arts; 800–899, literature and rhetoric; and 900–999, history, biography, and geography. These 10 main groups