It simply shows the world's Seven Summits -- the tallest mountains in the world, which together form a kind of grand slam for world-class mountaineers:
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But then below the chart are the rankings of a mountain's 'prominence.' Also called autonomous height, relative height, or simply prime factor, it's basically a measure of how tall a mountain is relative to its surrounding topography. So you actually learn a little bit about what it feels like to climb a given summit. If a mountain is tall but has a low prominence, then it probably doesn't feel all that dramatic -- you feel like you're on top of simple one mountain among many others. But mountains with higher prominence jut up from the land around them -- the loom over the surrounding landscape. Thus, when climbed, they offer a more dramatic sense of ascent and greater views. And once you're at the top, the give you more of a sense of being on the literal top of the world.
[Via Audree Lapierre]
