Abseiling (from the German: abseilen, "to rope down") is the process of descending a rope under control, used in rock climbing, mountaineering, caving and canyoneering; used to descend cliffs or slopes too steep to walk down.
It is also known as: rappelling (American English), abbing (British slang for "abseiling"), jumping (Australian slang) rap jumping (American slang), roping down, roping, seiling (Australian slang), snapling (Israeli slang), rappling (Hindi slang).
Helmets are worn to protect the head from bumps and falling rocks. A light source may be mounted on the helmet in order to keep the hands free in unlit areas.
Mechanical descenders include braking bars, the figure eight, the abseil rack, the "bobbin" (and its self-locking variant the "stop"), the gold tail, and the "sky genie" used by some window-washers and wildfire firefighters.