What do contour lines represent on a topographic map?

Terrain form and elevation.

On a topographic map, contour traces characterize the form and elevation of the land. They supply a three-dimensional perspective on a two-dimensional map by indicating the relative steepness or flatness of the terrain.

Every contour line connects factors of equal elevation. For instance, each level on a selected contour line could be precisely 1000 meters above sea stage. The gap between contour traces signifies the slope of the terrain – if the traces are shut collectively, it signifies a steep slope, whereas traces which are far aside characterize a gentler slope. Closed contour traces usually point out hilltops or depressions within the terrain.