Final answer:
Vernacular regions are hard to define due to their basis in individuals' mental maps or perceptions, and they are not bound by formal or physical characteristics. They often include cultural or historic regions.
Step-by-step explanation:
Vernacular regions are hard to define because they are usually people's "mental maps". In geography, these types of regions are perceived regions that exist based on an individual's perception or feelings towards an area. They are not necessarily bound by formal borders like administrative regions nor defined by physical or functional characteristics. Examples often include cultural or historic regions, or colloquial areas such as 'the Midwest' in the United States. While each person's mental map may vary, these regions usually have generally agreed-upon conceptual boundaries in a larger social context.
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