Mountain Climbing, Hiking Levels and the Yosemite Decimal System
Climbs of Colorado's Fourteeners can be classified as "walkable" or requiring a scramble (the use of hands and knees). Many climbs require more nuanced classification, however, and that's where the Yosemite Decimal System comes in handy. You'll often come across the classes of the YDS in the trail descriptions of individual peak pages.
The Yosemite Decimal System is a system for the difficulty of walks, hikes, and climbs used for mountaineering in the US. It was initially created by the Sierra Club in the 1930s for use in the Sierra Nevada, and has been a standard ever since.
The five classes are as follows, in order of increasing difficulty:
In addition, in the 1950s Class 5 was further broken down into sub-classes 5.1 (easiest) through 5.14 (most difficult) to describe rock climbing, which is generally avoided in this guide.