In rock climbing, a bolt is a permanent anchor fixed into a hole drilled in the rock as a form of protection. Most bolts are either self-anchoring expansion bolts or fixed in place with liquid resin.
While bolts are commonplace in rock and gym climbing there is no universal vocabulary to describe them. Generally, a bolt hanger is a combination of a fixed bolt and a specialized stainless steel hanger designed to accept a carabiner, whereas in certain regions a bolt runner describes a hangerless bolt (where the climber must provide their own hanger bracket and lock nut).
A climbing rope is then clipped into the carabiner. Increasingly, quickdraws are employed between bolt hangers and the rope to reduce drag when ascending, belaying and rappelling.
Bolts are also used both in aid climbing to actively aid ascent and sport climbing as a backup to catch a fall, where resting on or using one's protection to aid ascent is regarded as poor form.