Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Region is most commonly a geographical term that is used in various ways among the different branches of geography. In general, a region is a medium-scale area of land or water, smaller than the whole areas of interest (which could be, for example, the world, a nation, a river basin, mountain range, and so on), and larger than a specific site. A region may be seen as a collection of smaller units (as in "the New England states") or as one part of a larger whole (as in "the New England region of the United States"). Regions can be defined by physical characteristics, human characteristics, and functional characteristics.