Library of Congress Classification System (LC) - Used by most academic libraries and in other larger libraries. This is the system that is used here at Roberts Library with the exception of the Government Documents.
Superintendent of Documents (SuDocs) - Used by libraries with collections of materials published by the United States Government.
Dewey Decimal Classification System (Dewey) - Used by most public and K-12 school libraries.
Call Numbers - An Introduction
Materials in libraries have to be organized in some way so that things can be found once they have been placed on a shelf.
Each item is assigned a unique code, called a call number, to help with organization.
Call numbers are usually made up of numbers and letters and
sometimes include punctuation marks like dots or colons
Call numbers determine each item's exact location within a library
Call numbers are assigned to items so that they bring together
materials which are alike in some way, usually by subject
Classification Systems are the rules used to determine call numbers.
Most libraries, like public and academic libraries use standardized classification systems, but some (mostly special libraries) come up with their own classification system unique to their own needs and collections.
Knowing a little bit about them will make it much easier to find the items you are looking for at the library.