A boulder problem is a single bouldering route — a short sequence of moves on a boulder or wall, climbed without a rope. The name reflects bouldering's puzzle-like nature: each problem has a defined start and finish and is 'solved' by working out the right sequence. Problems are graded on the V-scale or Font scale.
An overhang is rock that is steeper than vertical, leaning out over the climber so gravity pulls you away from the wall. Overhanging climbing is strenuous and powerful, demanding good body tension and footwork to keep weight on the feet. The steepest overhangs, which go horizontal, become roofs.
A pinch is a climbing hold you grip by squeezing between your thumb on one side and your fingers on the other, like pinching a block. Pinches demand thumb and grip strength and range from wide, hard-to-span shapes to narrow ones. Body position that keeps the pinch loaded straight down makes it more secure.
A volume is a large, hollow geometric shape bolted onto an indoor climbing wall, over which smaller holds can be mounted. Volumes change the wall's angle and shape, adding three-dimensional, often slopey climbing that demands body tension and creative footwork. They are a defining feature of modern competition and gym bouldering.
A jug, also called a bucket, is a large, easy-to-grip climbing hold with a deep, positive edge you can wrap your whole hand around. Jugs are the most secure and beginner-friendly holds, often marking rests or the start of a route, and let climbers hang comfortably even when tired.
Climbing holds are the features — natural on rock or moulded on a wall — that climbers grip with their hands or stand on with their feet. They come in distinct types, from big friendly jugs to tiny crimps and rounded slopers, and each is gripped with a specific technique. Recognising hold types is fundamental to reading and climbing a route.
The girth hitch is a simple hitch that attaches a sling or loop of cord around an object — a tree, a harness tie-in point, or another sling — by passing the loop through itself. It's quick and handy but loses some strength at the choke point, so climbers avoid girth-hitching slings together at sharp angles under critical loads.
A stopper knot is a backup knot tied in the tail of another knot or at the end of a rope to keep the main knot from slipping or the rope from running through a device. Climbers add a stopper to back up a tie-in figure-eight and tie stopper knots in rope ends to avoid the deadly error of rappelling off the end.
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.
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.