What is the purpose of contour lines on a map?

Contour lines on a map are specifically designed to represent elevation change across the terrain. Each contour line connects points of equal elevation, allowing users to visualize the three-dimensional shape of the land on a two-dimensional map. By examining the spacing between these lines, one can discern the steepness of slopes—closely spaced lines indicate steep areas, while widely spaced lines suggest gentle slopes. This feature is crucial for a variety of applications, including hiking, urban planning, and environmental studies, as it helps users understand how elevation varies in a given area.

In contrast to this, other options like indicating road types, showing water sources, or identifying urban areas do not pertain to the specific function of contour lines, which is focused solely on elevation and topographical variations.