Abseiling ( /ˈæbseɪl/ or /ˈɑːpzaɪl/; from German: abseilen meaning "to rope down"), rappelling in American English, is the controlled descent down a rock face using a rope; climbers use this technique when a cliff or slope is too steep and/or dangerous to descend without protection. Rope Access Technicians also use this as a method to access difficult to reach areas at height for various industrial applications like maintenance, inspection, welding, etc. (See Rope access)

Slang terms for the technique include: rapping or rap jumping (American slang), deepelling (Canadian slang), abbing (British slang for "abseiling"), rappling (Hindi slang). The term rappel / rappelling is derived from the French language: French, recall, return, rappel, from Old French, recall, from rappeler, to recall: re-, re- + appeler, to summon.

The origin of the abseil is attributed to Jean Charlet-Straton, a Chamonix guide who lived from 1840–1925. Charlet originally devised the technique of the abseil method of roping down during a failed solo attempt of Petit Dru in 1876. After many attempts, some of them solo, he managed to reach the summit of the Petit Dru in 1879 in the company of two other Chamonix guides, Prosper Payot and Frédéric Folliguet, whom he hired. During that ascent, Charlet perfected the abseil.