A climbing harness wraps around the waist and upper thighs to anchor the climber to the rope. It distributes the force of a fall across the hips and the strongest parts of the legs, rather than concentrating it in a single point. A modern harness has a padded waistbelt, two padded leg loops, an adjustable rear riser strap connecting the leg loops to the back of the waistbelt, and gear loops for racking equipment.
The critical part is the belay loop — a small reinforced loop at the front of the harness that the rope is clipped or tied to. The waistbelt and leg loops connect through the belay loop at the tie-in point. Modern harnesses are tied in with a figure-8 follow-through knot through both the waistbelt and leg loop bridge, never just the belay loop.
Harness types vary by use: lightweight sport harnesses for competition, padded all-day harnesses for big-wall and trad climbing, slimmer ice climbing harnesses, and beginner harnesses with simplified buckles. Indoor gym climbers often use rental harnesses initially. When buying your first harness, get fitted in a shop — sizing matters more than features at the entry level.