You can consider the call number the address of the book in the library. Penfield Library uses the Library of Congress Classification system. This system organizes materials by subject area, and designates letters for each subject. Call numbers begin with these letters, with the result that similar materials are shelved together. Books are arranged alphabetically by call number. As you look for a specific book, you can browse the other books shelved nearby, which often leads you to additional sources.

You may also see a "collection code" before the call number, that tells you to look in a special place for your materials. For example, much of our popular fiction is kept in the "browsing" collection. The "availability" screen will give you all the details you need.