A library classification is a system of organization by which library resources are arranged according to subject. It is a implication of the Third law of Library & Information Science, which was given by Dr. S R Ranganathan.
There are many standard systems of library classification in use, and many more have been proposed over the years. However, in general, classification systems can be divided into three types depending on how they are used:
- Universal schemes which cover all subjects, for example the Dewey Decimal Classification, Universal Decimal Classification and Library of Congress Classification
- Specific classification schemes which cover particular subjects or types of materials, for example Iconclass, British Catalogue of Music Classification, and Dickinson classification, or the NLM Classification for medicine.
- National schemes which are specially created for certain countries, for example the Swedish library classification system, SAB (Sveriges Allmänna Biblioteksförening).