The legend indicates how cities are depicted with squares or dots, according to their sizes. It also illustrates the use of color to show different elevations and political entities. The systematic drawing of lines on a plane surface to represent the earth's parallels of latitude and the meridians of longitude is a convenient means of illustrating projection. A map projection may be established by analytical computation or may be constructed geometrically. Each projection gives the map reader a unique perspective on the arrangement of the continents and oceans.
Any map is a subjective generalization.
It cannot show everything that is actually there, no matter how large the scale, thus in a sense it is also a subjective document, reflecting the objectives or political orientation of the mapmaker. Map Scale Of critical importance to any map is the scale. Scale is the ratio between the distance between two points on a map and the actual distance it represents.