What is "aid climbing"

n. (context climbing English) a type of rock climbing characterized by using equipment to make upward progress, as opposed to using the equipment solely for safety or for belays.

Aid climbing is a style of climbing in which standing on or pulling oneself up via devices attached to fixed or placed protection is used to make upward progress.

The term contrasts with free climbing in which progress is made without using artificial aids: a free climber ascends by only holding onto and stepping on natural features of the rock, using rope and equipment merely to catch them in case of fall and provide belay.

In general, aid techniques are reserved for pitches where free climbing is difficult to impossible, and extremely steep and long routes demanding great endurance and both physical and mental stamina. While aid climbing places less emphasis on athletic fitness and raw strength than free climbing, the physical demands of hard aid climbing should not be underestimated.

Aid climbing is sometimes errantly referred to as class 6 climbing, since its reliance on ascent by one's equipment rather than merely being protected by it is regarded by purists as falling outside the traditional Classes 1-5 Yosemite Decimal System rankings that rely on making progress with one's hands and feet in direct contact with the rock alone. Aid climbing has its own ranking system, using a separate scale from A0 through A5.