An 'area' is a human categorization that is meant to differentiate different regions in the Far Plane that have several unique characteristics compared to its surroundings. In truth, many areas overlap with each other and do not have defining starts or ends.
They connect in varying, non-euclidian ways. In some parts they may transition in a gradient, in another the border is quite stark.
Sizes of areas are measured as small, medium, large, and expansive. Small areas are those which are easily explorable within a short amount of time, while expansive areas may never be fully explored due to their size.