What do contour lines represent on a map?

Contour lines on a map are used to represent elevation changes in the terrain. These lines connect points of equal elevation, allowing readers to visualize the shape and steepness of the land. When contour lines are close together, it indicates a steep slope, while lines that are spaced further apart signify a gentle slope. By interpreting these contours, one can understand the topography of an area, including hills, valleys, and plateaus, without any additional visuals. This feature is essential in various fields, including hiking, architecture, and urban planning, as it helps convey important geographical information about the physical landscape.

The other options refer to different types of mapping symbols that are used for specific purposes but do not relate to changes in elevation, making them less relevant in the context of contour lines.