The Library of Congress Classification (LCC) system divides knowledge into 21 main classes, which are further divided into subclasses. The main classes are:
Philosophy, psychology, religion
Language and literature
Arts and recreation
History and geography
Social and public welfare
Within each main class, there are many subclasses that allow for more specific organization and classification of materials. The LCC system is used by many libraries around the world, particularly in the United States, to organize and classify their materials in a way that makes it easy for patrons to find what they are looking for.