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University Library, University of Illinois at Urbana-Champaign

Library Organization and Classification Systems

This guide will help you understand the different classification systems in the library.

Dewey Decimal Classification

This classification scheme, designed by Melville Dewey in 1876, is used by many libraries on campus. Dewey divides knowledge into ten main classes with further subdivisions accompanied by decimal notation (for an extensive list of the classes and subdivisions, see our Dewey Decimal System page). This system allows for books on similar topics to be near each other on the shelves.

Infographic (Accessible View)

The Anatomy of a Call Number: Dewey Decimal System

Size Designation

Relates to the physical size of the book. A 'Q.' indicates a quarto while 'F.' indicates a folio.  In general, an item is considered a quarto when its height is between 29cm & 42cm, or its length is between 25cm & 35cm. It is labeled with either an upper or lower case 'Q.'.   Official rules state that an item is deemed a folio when its height exceeds 42cm or its length exceeds 35cm.