Hierarchy is a system of ranking and organizing objects such as organizations, individuals, or widgets, where each object of the system (except for the top element) is subordinate to another object.
With regards to this software, a hierarchy is the relationship between two or more entities of the same type by virtue of a parent-child identifier on one or both of the records. A record may have only one parent for a given Hierarchy Type.
With the Relationship view, the Hierarchy view allows you to see the same relationships in a tree view. The user can drag-and-drop within the hierarchies, and to reparent the relationships as well.