A blaze is a marker — usually a painted rectangle on a tree or rock, or a metal tag — used to mark a hiking trail's route. Different colors denote different trails, and a double blaze signals a turn or junction. Following blazes is a basic trail-navigation skill.
A cairn is a stack of stones built to mark a trail or route, especially above treeline or across rock where a worn path is hard to follow. Hikers use cairns to navigate; building unofficial ones can mislead others, so the principle is to follow established cairns rather than create new ones.
A switchback is a sharp zigzag in a trail that climbs a steep slope at a gentler angle, reversing direction repeatedly to ease the gradient. Switchbacks make steep terrain walkable and reduce erosion. Cutting straight across them — 'cutting switchbacks' — damages the trail and is discouraged.
An offwidth is a crack too wide to hand-jam but too narrow to fit your whole body, making it one of the most awkward and strenuous features to climb. Offwidth technique uses arm bars, chicken-wings, and stacked hands and feet wedged inside the crack, and it is notorious for being physical and hard to protect.
A chimney is a crack or gap in the rock wide enough to fit your whole body inside. Climbers ascend it by pressing against the opposing walls with their back, feet, hands, and knees — a technique called chimneying — rather than gripping holds. Chimneys are awkward and strenuous but can offer secure, restful positions.
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 roof is a section of rock that juts out horizontally, overhanging so severely that it runs parallel to the ground like a ceiling. Climbing a roof demands powerful, tension-heavy movement — heel and toe hooks, underclings, and core strength — to keep the body from swinging off, and pulling the lip is often the crux.
An edge is a climbing hold with a defined, flat lip that you grip with your fingertips or stand on with the edge of your shoe. Edges range from generous to razor-thin — where they become crimps — and they are the most common hold type on technical face climbs, rewarding precise edging footwork.
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 flake is a thin slab of rock partly detached from the main face, creating an edge or crack a climber can pull, pinch, or layback. Flakes range from solid, useful holds to loose, dangerous blocks, so testing a flake before fully weighting it is an important safety habit.