There are dozens of map types, including political maps, road maps, physical maps and topographic maps. In addition, National Geographic says maps may be categorized in terms of the type of projection used to display a three-dimensional globe on a two-dimensional surface.
Political maps are used specifically to show political boundaries such as the boundaries between countries, states or counties. Physical maps are used to show the natural geography of an area and may include features such as rivers, lakes, mountains and deserts. Road maps are used to show roads and other transportation routes, and topographic maps show area elevations. Maps are often a blend of multiple simpler types; for example, a political map may also show major roads and the physical features of an area.
Each map, with the exception of globes, uses some sort of projection. Projection maps distort distances and sizes of the areas displayed in order to fit the features of a globe onto a flat surface. Most maps use Mercator projection because it is adequate for most uses. While it grossly distorts regions near the poles, there is minimal distortion of small areas such as states. However, special-purpose maps such as flight maps or polar maps use other types of projection. At one point, according to About.com, there was a movement among geographers for the use of the lower-distortion but harder-to-read Robinson projection maps