The term hierarchy is used in network technology for the organization of structures. This concept of order is also used in object-oriented programming.
- A hierarchy is understood to be a strict hierarchy. The hierarchical structure is an organization form, which is characterized by a consistent, factual arrangement in groups, subgroups, sub-subgroups etc.. The individual groups may be interrelated or directly related to each other. Each group and subgroup of such a system can in turn be the starting point of another branching. All branches together form the overall hierarchical system. Graphically the hierarchy with its ramifications resembles a tree structure. Hierarchical structures occur in computers, networks, address structures and file systems.
- In object-oriented programming, hierarchy is the partial ordering of objects or classes according to a relationship defined between them. In most object-oriented languages, different, orthogonal hierarchies are used: the object hierarchy, which is based on the composition "part-of" relationship, and the class hierarchy, which is based on implementationinheritance. In some languages, the type hierarchy is distinguished from this.