Hierarchical, or hierarchy, refers to systems
that are organized in the shape of a pyramid. Items, such as objects, names, categories, or values, are represented as above, below, or at the same level as another item. Hierarchical systems are used in everyday life. For example, the army uses a hierarchy in that generals are at the top of the pyramid and privates are at the bottom. Similarly, the system for classifying plants and animals according to species, family, and genus is hierarchical. The term is derived from the Greek words hieros
, meaning sacred, and archein
, meaning rule or order.