Portraying the round earth on a flat map results in various kinds of distortions. This is because one must stretch and/or shear the image of the globe in order to flatten it out. Maps projections distort one or more of the following:
Conformal projections maintain true shape, Equal-area
projections maintain true size.
The type of map projection chosen depends on the purpose of the map (e.g. navigation, statistical representation, regional focus, relative location).
Cylindrical Projections, Mercator, Peters, The Peters Map Compared to the Mercator Map, Space Oblique Mercator
Azimuthal Projections, Berghaus Star, Gnomonic
Conic Projections, Equal Area Conic: North America