Basic map symbols include, but are not limited to, stars indicating political capitals, circles for towns or cities, inverted triangles for mountains and wavy lines for rivers. Map legends are essential tools that allow readers to understand what is represented on a map.
Basic symbols in the legend should be limited to the bare minimum necessary. For example, a simple map of nations during World War II may use one color to designate all the Allied Powers, another to indicate the Axis Powers and a third color to indicate those which stayed neutral. Use of colors as basic legend symbols extends to many other areas. A series of maps offered by the Association for Canadian Educational Resources employs colors to illustrate everything from age differences to climate biodiversity to wetland erosion patterns. Other map legends deal with far simpler circumstances. A map from Teach Engineering, for example, shows a rudimentary layout for a camping area, with a green triangle symbolizing the campsite, a dotted line for a hiking trail and two crossed lines indicating a peak.
Two of the most important and basic symbols the reader is likely to find in a map legend are directional arrows and scale markers. Directional arrows might point out a single direction relative to where the person is standing, such as North. This allows the person to establish all four directions and gain her bearings. Scale markers tell the reader, using simple ratios, how many times smaller the area's outline on a map is than the area it is actually depicting. A common ratio may be one inch on the map representing one mile in real space.