It certainly is not necessary to know how this system was designed or how books are given LC call numbers to use the library. But, the more you know about the system the better you will become at searching for and locating information.
Call numbers serve the purpose of grouping materials according to subject matter.
As mentioned above, the call number system used in this library is the LC Classification System. LC call numbers are normally a combination of letters and numbers arranged in 3 or 4 lines. If there are two letters remember that a single letter such as H comes before HA, and HM comes after HJ and before HX on the shelves. For instance, H represents Social Sciences not History, which would be found in the E's. You can find a quick reference guide to subject areas and their corresponding letter further down in this document.