Geographers divide areas into different regions so they can compare them, study them without an overwhelming amount of information, and understand how they work together as a system. By doing this, geographers can use smaller amounts of information to create a better understanding of human and physical patterns on Earth.
Regions can vary drastically in size from as large as a hemisphere to as small as a block of apartments. When geographers are selecting regions, they determine the boundaries by criteria other than the size. There are three main kinds of regions - formal, functional and vernacular.
The boundaries of formal regions are generally determined by politics, culture, economy and physical features. Examples of formal regions include Brazil, the Alps, the Jewish community or fruit growing areas.
Functional regions are used for service areas such as areas served by a particular delivery company or cable company. There are two kinds of functional regions - nodal and network. A nodal region is defined by point-to-point activity such as phone calls placed to New York over a given period. However, a network region describes a web of activity such as delivery routes.
Vernacular regions are determined by perception and can drastically vary from person to person. Examples of vernacular regions include Midwest and Uptown.