Hierarchies usually look like an outline or tree or directory structure.
The first level of the hierarchy identifies the whole set of information to be divided, the second level breaks that information into main categories, the next level breaks those categories into sub-categories, and so on. In contrast to clustering , which involves an informal division of information, hierarchical organization is a formal method that follows strict guidelines for categorizing information. Hierarchical organization helps people make sense of masses of information. For example, families preparing to leave on a vacation will often divide what they need to buy into categories based on the shopping they must do. Suppose, for instance, you are writing a progress report informing supervisors of your research on a project.