What is generally the primary purpose of contour lines on a topographic map?

Contour lines on a topographic map serve to indicate slope and elevation changes by connecting points of equal elevation. This helps the viewer understand the terrain's relief, showing how steep or gentle the slopes are in a given area. The closer together the contour lines are, the steeper the slope; conversely, lines that are spaced further apart indicate a gentler slope. This visual representation of elevation changes enables users, such as hikers, engineers, or planners, to navigate and assess the landscape effectively. By understanding contour lines, one can better comprehend the physical features of the land, including hills, valleys, and any other forms of elevation.