Hierarchy

A hierarchy is an ordering of persons, ideas, or constructs from less to greater importance, in a tiered organizational structure. Organizations may have a hierarchy, both formally and informally: for example, the Senate formally has no internal hierarchy, but informally, senior Senators may "rank" above junior Senators.

Intellectually, ideas may be expressed in a hierarchical form. An idea common in philosophy is the "hierarchy of needs," a theory proposed by Abraham Maslow, who argued that each individual must meet different needs in ascending order before attaining self-actualization, the pinnacle of human self-awareness.