4.6 Library Classification : Subjects

Within a library collection, materials are typically organized by subject. Librarians assign a call number based on a work's subject and sources are then shelved by that call number so that anyone browsing the shelves will find most of the titles on a subject together.

The subject classification system translates a work's subject and author or title into a code (call number) that determines where it will be shelved.

The example below illustrates how the Library of Congress subject classification system is used to assign call numbers for the book Hidden Manna: A Theology of the Eucharist by James T. O'Connor, published in 2005.
 

Subject Classification		How it works
Instructions: Click on Go, and call number (one Library of Congress, one Dewey Decimal) are rearranged with explanation of each part of number for above book, shown in a graphic.
Library of Congress: Used in most college, university, and research libraries because it handles large collections.