A (Greek hieros sacred, arkho rule) is a system of rankinging and organizing things. Different fields use the word in slightly different ways, but a particular definition, which the article will attempt first, captures the core of almost all uses. Originally, "hierarchy" meant "rule by priests". Since hierarchical churches such as the Roman Catholic and Eastern Orthodox churches had tables of organization that were "hierarchical" in the modern sense of the word, the term came to refer to more general organizational methods.
Illustration: A hypothetical hierarchical organization for an encyclopedia. Each node "contains" all the sections below it, e.g. the culture section contains the art section and the craft section.
A hierarchy is based on an asymmetrical relationship, such as "is the boss of", "is part of", or "is better than". Such relationships are "asymmetrical" in the sense that if they "work one way", they don't "work the other". For example, if Sally is the boss of Jim, then Jim is not the boss of Sally. When two nodes are related, one is designated the "superior" (or sometimes the "parent") and the other the "subordinate" (or sometimes the "child"). In the intuitive case of the "is the boss of" relation, the boss is the superior and the employee is the subordinate.
A hierarchy's asymmetrical relationship can link entities in one of three ways: directly, indirectly, or not at all. The illustration shows a direct link between the craft and culture sections; the craft section is directly linked to the culture section by the "contains" relationship. This is akin to how your boss is directly in charge of you. In contrast, the illustration shows an indirect link between craft and encyclopedia; the craft section is only "contained" by the encyclopedia as a whole by virtue of being "contained" by the culture section. This is akin to how the CEO of a company is in charge of a factory worker only via middle management. Finally, there is effectively no link between the art and the craft sections; neither section contains the other. This is akin to two co-workers, neither of whom is the other's boss.
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Every member is reachable from any other by following the relationship in either direction, but there is no way of coming back to a particular member by always following the relationship in the same direction.
Many human organizations, such as businesses, churches, armies and political movements are structured hierarchically, at least officially; commonly superiors, called bosses, have more power than their subordinates. Thus the asymmetrical relationship might be "has power over". (Some analysists question whether power "really" works as the traditional organizational chart indicates, however.) See also Chain of command.
Feminists talk about a hierarchy of gender, in which a culture sees males or masculine traits as superior to females or feminine traits. In the terms above, these feminists present us a hierarchy of only two nodes, "masculine" and "feminine", connected by the asymmetrical relationship "is valued more highly by society". An example of this usage:
The hierarchical nature of the dualism - the systematic devaluation of females and whatever is metaphorically understood as "feminine" - is what I identify as sexism. (Nelson 1992, p. 106)
Note that when feminists and other social critics use the word hierarchy, they usually hope to evoke negative connotations; hierarchy, for them, is a bad thing. In these contexts, hierarchy and power structure are basically synonyms.
The pitches and form of Tonalmusic are organized hierarchically, all pitches deriving their importance from their relationship to a tonickey, and secondary themes in other keys are brought back to the tonic in a recapitulation of the primary theme. Susan McClary connects this specifically in the sonata-allegro form to the feminist hierarchy of gender (see above) in her book Feminine Endings, even pointing out that primary themes were often previously called "masculine" and secondary themes "feminine."
The Wikipedia community is noteworthy for being not overtly hierarchically structured, as no contributor possesses inherently higher standing than another, excepting certain limited "admin" and "developer" powers restricted to a few. However, some would counter that although there is no explicit hierarchy there are social norms which make contributions unequal, as some contributors have more influence because their edits command higher respect.
Those who frequent Wikis might label Wikipedia's organization "wikiarchical".
nature of the hierarchical relationship: part-whole hierarchy, containment hierarchy, inheritance hierarchy, responsibility hierarchy, control hierarchy
