Call numbers are the system that people use to find the specific books they're looking for in a library. Without a very specific system of organization, it would be virtually impossible to find a certain title or subject in a collection of thousands of books. While the numbers and letters may seem foreign and overwhelming at first, it isn't difficult to learn how to use them. Understanding how it all works will allow you to find any book or topic area in a library in minutes.
Most libraries now use computerized card catalogs. When trying to find a book, begin by doing a search for the topic or title you're looking for. Look at the results, and write down the call numbers of the best ones to find them on the shelves. Each book has its own call number, which often includes letters as well as numbers. It can be found on the spine of the book. Books are always arranged in numerical and alphabetical order on the shelves. When looking at a shelf, the numbers increase from left to right and top to bottom - just like reading a page of print. Remembering the rule, "Nothing comes before something," can also help locate books. For example, 852 would come before 852.1, and J is before JB.
Call numbers are not assigned randomly. The first letter or number refers to a broad category of subjects. In the Dewey decimal system, for example, everything in the 900 is history. Getting more specific, 930 are ancient history, with every call number that begins with 932 being about Ancient Egypt. The more digits a call number has, the more specific the book's subject is.
There are two main systems for library call numbers. The Dewey decimal system is the one that most people are familiar with. It is typically used in public libraries and in elementary, middle, and high schools. Books are usually divided into two main categories of fiction and non-fiction. There are often separate sections for a few special genres like biographies and westerns, as well. The call numbers of non-fiction books start with numbers. They often have a cutter number below the Dewey decimal number, which begins with the first letter of the author's last name. Then, there may be the year of publication. Fiction books are usually classified under "F" or "Fic" followed by the author's last name.
Academic libraries, including those found at colleges and universities, generally use the Library of Congress system for call numbers. This is a little more complicated than the Dewey decimal system, because it begins with letters instead of numbers. The general principles are the same, though. Each letter of the alphabet refers to a broad subject area, which is broken down into more specific topics. Here is an outline for this system.