A hierarchy is an arrangement of objects, people, elements, values, graes, orders, classes, etc., in a ranked or graduated series. The word derives from the Greek ἱεραρχία (hierarchia), from ἱεράρχης (hierarches), "president of sacred rites, high-priest" and that from ἱερός (hieros), "sacred" + ἄρχω (arkho), "to lead, to rule". The word can also refer to a series of such items so arranged. Items in a hierarchy are typically thought of as being "above," "below," or "at the same level as" one another.