In geography, "relief" refers to the highest and lowest elevation points in an area. Mountains and ridges are typically the highest elevation points, while valleys and other low-lying areas are the lowest.
Relief is essential to understanding the topography of an area. Consequently, map makers display different elevations through several methods. Contour lines show elevation change between consecutive lines and are frequently used on flat maps. The closer the lines are to each other, the steeper the elevation. Color is also used to show elevation: brown for higher elevation and green for lower elevation. Globes allow viewers to experience relief in 3-D.