In this second module let's get familiar with one of the most important concepts: topography. Topographic maps use contour lines to visualize the elevation of the terrain. Elevation is essential for planning your hiking routes. A contour line connects points of equal elevation or altitude. The simple example below shows how a 3D hill is visualized / projected on a 2D topographic map using contour lines. Every inward contour indicates an increase of 10m in altitude. The peak is represented by the innermost contour corresponding to 80m altitude. Contours on the right (East) are more widely spaced indicating a more gradual slope. Contours on the left (West) are closer indicating a steeper gradient. Contours are essential for trail planning in the mountains. Nearly all maps show contour lines to visualize the topography of the landscape.