Map projections. Computer artwork showing a selection of different map projections used to map the Earth. Map projections are necessary for creating maps. A map projection is any method of representing the surface of a sphere, such as the Earth, or other three-dimensional body on a plane (flat surface). All map projections distort the surface in some fashion, but depending on the purpose of the map, some distortions are acceptable and others are not; therefore different map projections exist in order to preserve some properties of the sphere-like body at the expense of other properties. There is no limit to the number of possible map projections.