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MSJC > Libraries > Menifee Valley Campus Library > Understanding Call Numbers

Understanding Call Numbers

Have you ever wondered how library books are assigned their places on the shelves? Did you know that the call number -- the number placed on the spine of the book -- is a code which provides valuable information about the book? This page will provide an introduction to understanding and using library call numbers.

What are call numbers for?

Each book in the library has a unique call number. A call number is like an address: it tells us where the book is located in the library.
Call numbers appear on the spines of books.
illustration of book spine with a call number written top-to-bottom and computer screen with call number written left-to-right 
Note that the same call number can be written from top-to-bottom, or left-to-right.

Menifee Valley Campus College Library, like many academic libraries in the U.S., uses Library of Congress Classification for call numbers. This system uses a combination of letters and numbers to arrange materials by subjects.

Reading Call Numbers

illustration of call numbers in four rows, first alphabetic, second numeric, third alpha-numeric as a decimal, fourth is year published

Putting Call Numbers in Shelf Order

To understand how call numbers are put in order in Library of Congress Classification, again look at each section of the call number.
illustration of sample call numbers ordered by call number sections read top-to-bottom or left-to-right

What does the call number mean?

Remember that Library of Congress Classification arranges materials by subjects. The first sections of the call number represent the subject of the book. The letter-and-decimal section of the call number often represents the author's last name. And, as you probably recall, the last section of a call number is often the date of publication.
illustration of the meaning of the call number: the first two lines describe the subject, the third represents the author's last name, and the fourth is the year the book was published

Why is this important to know?

Because books are classified by subject, you can often find several helpful books on the same shelf, or nearby. For example, within the same call number LB2395, there are other guides for college study.
illustration of ordered call numbers of books of similar subjects 
Since Library of Congress Classification arranges materials by subjects, knowing the letter(s) for your subject area gives you a place to start browsing the shelves. Which letters represent your subject? Click here to learn about the Library of Congress Classification Table.