We speak about places such as the Great Plains, the Caribbean, Europe, or sub-Saharan Africa. These are all regions. In the past geographers believed there were natural and God-given regions and the task of geography was to discover those regions. As that search continued it became apparent to geographers that regions were mental constructs. By interpreting landscapes and other information geographers decide how to divide the surface of the earth into regions.
All regions have certain characteristics in common.
They have a location, boundaries, and area. We talk about formal regions that are homogenous and functional regions defined in terms of functions or interactions of different kinds. People may have quite contrasting views as to how the earth should be regionalized. Different groups perceive the amenities and disamenities of different parts of the world and make regions according to their perception or understanding of what the world is like. Whenever geographers make a region they must be aware that other people can come up with equally valid classifications.