A figure eight on a bight is a figure-eight knot tied in a loop (bight) of rope rather than the end, creating a strong, easy-to-inspect loop anywhere along the rope. Climbers use it to clip into anchors, attach to the middle of a rope, and build master points, sharing the figure-eight's strength and visibility.
The alpine butterfly is a knot that puts a secure, load-bearing loop in the middle of a rope without needing the ends. Climbers use it to isolate a damaged section of rope, to tie into the middle of a rope on a glacier team, and to clip a third climber into the system. It can be loaded in any direction.
The water knot, or ring bend, is the standard knot for joining the ends of flat webbing into a sling or runner. It's a retraced overhand knot that holds well in webbing, where many other knots slip. The tails must be left long and the knot checked regularly, since water knots can slowly creep loose over time.
The bowline is a knot that forms a fixed loop at the end of a rope, used by some climbers as an alternative tie-in and to attach the rope to anchors or trees. Its main advantage over the figure-eight is that it unties easily even after heavy loading, but it must be backed up, since an unsecured bowline can shake loose.
Climbing knots are the small set of knots, hitches, and bends that climbers rely on to tie into the rope, build anchors, rappel, and perform rescues. A handful do almost everything — the figure-eight to tie in, the clove and munter hitches at the anchor, and friction hitches like the prusik for ascending and backups.
Back-clipping is a dangerous lead-climbing error where the rope is clipped through a quickdraw the wrong way, so it runs up against the carabiner's gate side rather than the spine. In a fall, the rope can press the gate open and unclip itself from the draw. Climbers learn to clip so the rope exits over the front of the carabiner.
Active protection is trad climbing gear with moving parts that grips the rock through a spring mechanism — chiefly spring-loaded camming devices (cams). It can protect parallel-sided and flaring cracks where passive gear won't hold, at the cost of more weight, expense, and maintenance. It contrasts with passive protection like nuts.
Passive protection is trad climbing gear with no moving parts that holds by wedging into a constriction in the rock — chiefly nuts and hexes. It is light, cheap, and durable, and works best where a crack pinches down. It contrasts with active protection like cams, which use a spring mechanism to grip.
Fall factor is a number describing the severity of a climbing fall, calculated as the distance fallen divided by the length of rope available to absorb it. It ranges from 0 to about 2 — higher factors mean harsher, higher-force falls. Because it depends on rope length, a short fall low on a pitch can be more severe than a longer one higher up.
Equalization is the principle of rigging a climbing anchor so the load is shared between its individual points rather than resting on one. A well-equalized anchor distributes force across two or more pieces, adding redundancy so no single point is overloaded. It is a core concept in anchor building, alongside redundancy and limiting extension.