The Dewey Decimal System works as a library classification system by assigning library materials numbers corresponding based on subject matter. The system divides the materials into 10 classes broken down into 10 divisions, which are in turn broken down into 10 sections. A book's Dewey Decimal System number determines its physical location in a library, making it easy for library patrons to find general topics and individual volumes.
Under the Dewey Decimal System, libraries usually separate fiction from nonfiction and organize it alphabetically according to author, although the number system allows for fiction categorization. In nonfiction sections, each volume generally has a number on the spine, with the first digit representing the book's class, the second its division and the third its section.
For instance, class 400 represents language, class 500 represents science and class 600 represents technology. Within the classification of language, 410 represents the division of linguistics, 420 the division of English language and 430 the division of German language. Within the division of linguistics, 412 represents the section of etymology, 413 represents dictionaries, 414 phonology and 415 grammar. After these broader designations, the Dewey Decimal System assigns fractional decimals to further pinpoint subject matter such as geographic and temporal details, bibliographic forms, and language.