Travelers on land need somewhat different information from those at sea. The globe is the best way to show the relative positions of places, but a globe that can fit in a ship's cabin cannot show the detail needed for navigation. Flat maps distort the placement of features, but can show great detail and are portable. The transformation of map information from a sphere to a flat sheet can be accomplished in many ways, called projections. Mapmakers have invented projections that show distances, directions, shapes, or areas as they are on a globe, at least partially.
Different projections have different advantages and disadvantages.
Orthographic projections, for example, show shapes as they appear when the globe is viewed from space. Equal-area projections do not distort the size of areas but do distort their shapes. Conformal projections are those on which the scale is the same in any direction at any point on the map. Many projections retain one geometric quality, and a few retain more than one quality, but no single projection can accurately portray area, shape, scale, and direction. The Mercator projection was designed by Flemish cartographer Gerardus Mercator in 1569 to show compass directions as straight lines in all directions from all points on the map.