Types of Maps

Choropleth Map

Choropleth Map - Wikipedia defines this map as a "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."

Dot Map

Dot Map - According to www.earthonlinemedia.com, a dot map is one that "uses dots to illustrate the presence of the phenomenon on a map. A dot may equate to one or several units of measurement. Dot maps are especially useful in visualizing the frequency of occurrence or density of a mapped variable." 

Isarithmic Map

Isarithmic Map - www.earthonlinemedia.com defines this map as a map that "uses isolines, lines that connect equal values, to illustrate continuous data such as elevation, air pressure, and precipitation."

Proportional Symbol Map

Proportional symbol maps (also known as graduated symbol maps) are used in Cartography to visualize quantitative data associated with specific locations. For a given point on a geographic map, a symbol (usually a disk or a square) is scaled such that its area is proportional to the numerical value associated to the point. This scaled symbol is then placed at that point. (Source www.mappingignorance.org)