Topic summary
Relative height
Extracted from the Wikipedia article Topographic prominence.
In topography, prominence (also referred to as autonomous height, and shoulder drop in US English, and drop in British English) is the relative height of a mountain or hill's summit relative to the lowest contour line encircling it but containing no higher summit within it. It is a measure of the independence of a summit. The key col ("saddle") around the peak is a unique point on this lowest contour line. The parent peak (if any) is some higher mountain, selected according to various criteria.