Library Classification Systems
Within a library collection, materials are typically organized by subject. Librarians assign a call number based on a work's subject. You can think of a call number as an “address” for the book or item. Sources are then shelved by that call number so that anyone browsing the shelves will find most of the titles on a subject together.
There are two main subject classification systems that translate a work's subject and author or title into a code (call number) that determines where it will be located on the shelf. These systems are the Library of Congress (LC) and Dewey Decimal.
The activity at the right illustrates how the two main subject classification systems, Library of Congress and Dewey Decimal, are used to assign call numbers for the book, An Inconvenient Truth by Albert Gore, published in 2006, which presents research documenting the fast pace and wide scope of global warming.
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Activity: Parts of a Call Number
For more information about these classification systems, follow the links below:
Library of Congress Classification Outline
Superintendent of Documents (SuDocs) (for US government documents)
