Belaying is a variety of techniques climbers use to create friction within a climbing system, particularly on a climbing rope, so that a falling climber does not fall very far. A climbing partner typically applies tension at the other end of the rope whenever the climber is not moving, and removes the tension from the rope whenever the climber needs more rope to continue climbing.
The term “belay” also means the place where the belayer is anchored; this is typically the ground or a ledge, but may be a hanging belay, where the belayer themself is suspended from an anchor in the rock.