One way to classify maps is into two basic categories — reference maps and thematic maps. General reference maps include road maps and political maps that most people are familiar with, as well as base maps such as topographic maps, satellite image maps, and hydrologic (rivers and water bodies) maps.
Thematic maps, as the name implies, shows a theme, such as land use, ecoregions, traffic, crime rate, or population change. A reference map might show the locations of cities, while a thematic map might represent the population or growth rate of those cities. A reference map might show the locations of banks, while a thematic maps might show the average income or median housing price in an area.
Bring to mind or revisit the maps from the Esri Map Book you examined in the previous section. Which of these would you describe as a general reference map vs. a thematic map?