A map is a graphic representation of a place. There are many different types of maps that have different uses. Since a map is 2-dimensional representation of a 3-dimensional world, compromises must be made. Different maps differ in the relative accuracy of the depiction of the area, the shapes of objects, actual distances, and compass direction. Maps that accurately relect area are often called equal-area maps (an example is the Albers equal-area conic map). Maps that maintain the shape of objects are called conformal. Maps that correctly show the distance between areas are often called equi-distant maps (note that the shortest distance between two points on a map is generally not a straight line. but a curve). Navigational maps need accurate compass directions maintained on the map (like the Mercator map).