Map symbols may include point markers, lines, regions, continuous fields, or text; these can be designed visually in their shape, size, color, pattern, and other graphic variables to represent a variety of information about each phenomenon being represented.
Features such as buildings, cities, roads, lakes, and countries are geographic objects that are often portrayed on maps using symbols.
Geographers and cartographers usually categorize properties according to the classification system of Stanley Smith Stevens, or some revision thereof, such as that of Chrisman.
Jacques Bertin, a French cartographer, developed the concept of visual variables in his 1967 book, "Sémiologie Graphique.
"[8] Bertin identified seven main categories of visual variables: position, size, shape, value, color, orientation, and texture/grain.
The most important hierarchy is the thematic symbols and type labels that are directly related to the theme.
From this we see that the symbols are the single most important thing to build a good visual hierarchy that shows proper graphical representation.
When producing a map with good visual hierarchy, thematic symbols should be graphically emphasized.