In classification, the term “hierarchy” refers to a system of organization in which items are arranged in a series of levels or categories, with the most general categories at the top and the most specific categories at the bottom. This creates a logical structure that allows items to be grouped and organized in a meaningful way.
For example, in the Dewey Decimal Classification system, the main categories are represented by the digits 0-9, and the subcategories are represented by decimal numbers. This creates a hierarchy of categories, with the most general categories (represented by the digits 0-9) at the top, and more specific categories (represented by the decimal numbers) at the bottom.
In general, hierarchies are used in classification systems to create a logical and organized structure for the items being classified, making it easier to locate and access specific items. Hierarchies can also be used to reflect the relationships between different items or categories, and they can be used to represent complex or nuanced relationships in a clear and concise way.