There are several standard systems of library classification that are widely used in libraries around the world:
Dewey Decimal Classification (DDC) – This is a widely used library classification system that organizes materials according to subject matter. It is based on a hierarchical structure, with 10 main classes at the top and more specific categories and subcategories below them.
Library of Congress Classification (LCC) – This is another widely used library classification system that is used primarily in academic and research libraries in the United States. It organizes materials according to their intended use or audience, rather than their subject matter.
Universal Decimal Classification (UDC) – This is a library classification system that is used in many countries around the world, and it is based on a decimal numbering system that is similar to the Dewey Decimal Classification system.
Anglo-American Cataloguing Rules (AACR) – This is a set of standards and guidelines for cataloging and classifying library materials, and it is used in many libraries around the world.
Resource Description and Access (RDA) – This is a more recent library classification system that is based on the principles of linked data and the Semantic Web. It is designed to be more flexible and adaptable than older systems, and it is increasingly being adopted by libraries around the world.
These are just a few examples of standard library classification systems. There are many other systems in use, and the choice of which system to use often depends on the specific needs and goals of the library.