A cartogram is a map in which some thematic mapping variable – such as travel time, population, or GNP – is substituted for land area or distance. The geometry or space of the map is distorted, sometimes extremely, in order to convey the information of this alternate variable.
A choropleth map (from Greek χῶρος ("area/region") + πλῆθος ("multitude")) is a thematic map in which areas are shaded or patterned in proportion to the measurement of the statistical variable being displayed on the map, such as population density or per-capita income.
An Isarithmic map is a type of Thematic map that represents a continuous field using line and/or region symbols to connect places of similar value. It is sometimes called a heat map, although the term heat map should only be used for one type of isarithmic map that represents density.