A piton is a steel or iron spike — typically 5 to 15 cm long — that climbers hammer into cracks in rock to create a fixed anchor point. The eye of the piton accepts a carabiner, which clips into the rope to protect a fall. Pitons are used in traditional, alpine, and big-wall climbing, but rarely in modern sport climbing or bouldering.
Pitons come in several shapes for different crack widths and orientations: knifeblades for thin cracks, lost arrows for medium cracks, angles for wider cracks, and bongs for very wide cracks. Each is driven in with a hammer until it sits firmly and emits a clear ringing tone — the sign of a solid placement.
Modern climbing has largely moved away from pitons because they damage rock and remain in place permanently, scarring routes for future climbers. Removable protection like cams and nuts is now preferred. Pitons remain essential in alpine routes and aid climbing where temporary placements are not feasible. The word comes from the French "piton," meaning "peak" or "pin."