[2] Simul-climbing is different from a rope team (which can involve larger groups) and short-roping [fr] (used by guides with their clients), which are used for flatter terrain that doesn't typically need protection points.
[2][7] Simul-climbing is most commonly used by experienced alpinists on very long alpine climbing routes so they can move quickly on terrain that both climbers are very comfortable with, but which is sufficiently exposed to require protection.
[3][9][10] Examples are long sharp alpine ridges or aretes or easier-angled rock slabs and couloirs (see images).
[3][4] Alex Honnold and Tommy Caldwell considered their ability to simul-climb grade 5.10 rock climbing routes as critical to their award winning traverse of Cerro Chaltén Group in 2014.
[12] A safer alternative to simul-climbing for steep big wall routes is the technique of short-fixing, where the leader effectively sets up a fixed rope for the second climber to ascend while the leader simultaneously continues up the next pitch using a rope solo climbing technique.