Regionalization is the process of dividing an area into smaller segments or regions. For example- a country is divided into states and provinces.
The geographers regionalize the areas into smaller units so they could study the specific areas, and conduct desired researches, share ideas and topics effectively. This process isn't about creating regions as much as it is about identifying regions that already exist.
There are three types of regions divided:
a- the formal region
b- the vernacular region
c- the functional region