The craft of climbing has been developed to avoid two main types of danger: the danger of things falling on the traveller and the danger of the climber falling himself. The things that may fall are rocks, ice and snow; the mountaineer may fall from rocks, ice or snow, or into crevasses in ice or snow. There are also dangers from weather. Thus in all there are eight chief dangers: falling rocks, falling ice, snow-avalanches, falls from difficult rocks, falls from ice slopes, falls down snow slopes, falls into crevasses, dangers from weather. To select and follow a route avoiding these dangers is to exercise the climber's craft.
