Colon Classification is a system of library classification developed by S.R. Ranganathan in the 1930s. It organizes knowledge into a hierarchical structure using a combination of letters and numbers, allowing for a flexible arrangement of subjects. This method emphasizes the relationships between different topics, making it easier to locate and retrieve information. The classification system is based on five fundamental categories known as facets: Personality, Matter, Energy, Space, and Time. Each facet can be further divided into sub-facets, creating a detailed and comprehensive framework for organizing books and other materials in libraries.