The Prusik knot is a type of climbing knot used to create a loop that can slide along a rope but will grip tightly when weight is applied. It is commonly used in rock climbing, canyoning, and mountaineering for ascending or descending a rope safely. To tie a Prusik knot, a smaller loop of rope, known as a Prusik loop, is wrapped around a larger rope several times. When tension is applied, the knot tightens and holds securely, allowing climbers to move up and down the rope while maintaining safety.