A climbing wall is an artificially constructed wall with grips for hands and feet, used for climbing. Some are brick or wooden constructions, but on most modern walls, the material most often used is a thick multiplex board with holes drilled into it. Recently, manufactured steel and aluminum have also been used. The wall may have places to attach belay ropes, but may also be used to practice lead climbing or bouldering.
Each hole contains a specially formed t-nut to allow modular climbing holds to be screwed on to the wall. With manufactured steel or aluminum walls, an engineered industrial fastener is used to secure climbing holds. The face of the multiplex board climbing surface is covered with textured products including concrete and paint and/or polyurethane loaded with sand. In addition to the textured surface and hand holds, the wall may contain surface structures such as indentions (incuts) and protrusions (bulges), or take the form of an overhang, underhang or crack.
Some grips are formed to mimic the conditions of outdoor rock, including some that are oversized and can have other grips bolted onto them.
Gym climbing is becoming an increasingly popular urban sport and provides many people with the opportunity to try some aspects of the sport of rock climbing. Bouldering gyms focus on bouldering rather than roped climbing.
Other types of walls include slabs of granite, concrete sprayed on to a wire mesh, pre-made fiberglass panels, manufactured steel and aluminum panels, and textured fiberglass walls.
Grips come in different colours, those of the same colour often being used to denote a route, allowing routes of different difficulty levels to be overlaid on one another. Coloured tape placed under climbing holds is another way that is often used to mark different climbing routes. In attempting a given route, a climber is only allowed to use grips of the designated colour as handholds but is usually allowed to use both handholds and footholds of the designated colour and surface structures and textures of the "rockface" as footholds.
The grade (difficulty) of the route is usually a consensus decision between the builder of the route and the first few people who climb the route.
Many indoor climbing walls have people who are assigned to set these different climbing routes. These people are called route setters.
UK Climbing Wall Manufacturers Association: CWMA Website