Creating a system composed of interrelated subsystems, each of the subsystems being in turn hierarchic in structure until the lowest level of elementary subsystem is reached. Hierarchies are of many types: social, psychological, linguistic, conceptual, genetic, historical etc. Structural hierarchies are composed of objects classified by spatial whole/part relations and may include inorganic hierarchies (from atoms to galaxies) or organic hierarchies (from atoms to communities). Control hierarchies are structural hierarchies in which each higher level imposes additional constraints on the degrees of freedom of its parts, as opposed to free hierarchies which have no causal relationship between the levels.
Hierarchical structure and combination into systems of ever higher order is characteristic of reality as a whole and of fundamental importance especially in biology, psychology, and sociology. It is an essential feature of stable complex systems, whether they are inanimate systems, living organisms, social organizations, or patterns of behaviour, and such systems tend to evolve more quickly when hierarchically organized. As a tree structure, hierarchies may serve to represent evolution as a process, and its projection in taxonomic systems; it may equally represent the step-wise differentiation in embryonic development; it may serve as a structural diagram of the parts-within-parts architecture of organisms or galaxies; or as a functional schema for the analysis of instinctive behaviour by ethologists; or of the phrase-generating machinery by the psycholinguist.
Hierarchy is also the most conspicuous part of the formal structure of any social organization. (As such, it has frequently been falsely identified with the totality of formal structure, and the adjustment of hierarchic relationships has been falsely identified with the totality of the administrative process). The essence of hierarchy is then the distinction between the role of superior expected to exercise authority over one or more subordinates, who in turn function as superiors with respect to a lower level of subordinates.
The hierarchy of needs, developed by Maslow, describes five stages in human motivation: (1) Physiological needs, which cover basic biological drives (sex, food and drink, sleep and avoidance of pain). This is the most primitive condition; (2) Safety needs, which predominate when physiological needs are met and the desire is for security, change is looked on as a threat, and thinking is in black-and-white terms. Authoritarianism is typical of this level; (3) Love-belongingness emphasizes membership of a group, warm human relations and the goodness of conviviality; (4) Need for esteem, when a person has a feeling of self-worth and values being looked up to for his or her ability more than simply belonging to a group; (5) Self-actualization, when a person's reference group has narrowed from people in general, then colleagues, to finally the person himself. Personal development and self-exploration become of the greatest importance. Although no one person is totally at one stage, the lower stages have to be satisfied before the higher stages appear, and each person has one stage which predominates. Sudden loss at a lower stage will cause temporary reversion to that stage while the need is attended to.