Although skilled mountaineers may choose not to use ropes on hard climbs, for instance to save time in a dangerous situation, the rule for scrambles is that hands need be used only for balance, not to support any of the climber's weight. In practice this means the terrain will be approximately the steepness and difficulty of a ladder; the footholds will be large and the climber will be able to stand upright.
In the US, scrambling is Class 3 in the Yosemite Decimal System of climb difficulties, and Easy in the British system.
Many, if not most, of the world's mountaintops may be reached by walking or scrambling up their least-steep side. These routes are not always obvious, but mountaineering books generally mention them; they are often used as the safe and easy way to descend from a more difficult route.
Some guide books on scrambling may rate the routes as follows: