What is a formal region functional region and a functional region?

Formal are defined based on cold hard facts, such as population, per capita income of the people who live there, or even temperature.

Functional regions are organized around a focal point, that include areas that are linked to them through communication patterns, transportation routes, or even television broadcasts.

Perceptual regions reflect human feelings and attitudes about areas, they are based more on opinions than facts.

If you ever hear someone refer to a neighborhood as a place where "most of the people who" are members of an ethnic group, work in a certain profession, or have a certain set of ideas live without having taken a formal poll to determine the facts, they are talking about a perceived region.