What a Dewey decimal system number means?

The Dewey Decimal System is a library classification system that organizes books and materials into specific categories based on subject matter. Each number consists of three digits followed by optional decimals, indicating the main topic, subtopics, and further subdivisions. For example, the number 636.7 represents "Animal husbandry," with the first three digits denoting the broader category and the decimal specifying a more specific area within it. This system allows for efficient organization and easy retrieval of library materials.