Prusik Knot (Triple Sliding Hitch) Details
History: The Prusik knot was developed in 1931 by Dr.Karl Prusik (sometime president of the Austrian Mountaineering Club and often misspelled "Prussik".) It appears to be identical in structure to a knot described by Ashley for hoisting a spar. (ABOK # 1763, p 300), but Ashley did not name this knot and did not describe the slide and grip feature.
Structure: The knot requires a "Prusik Loop" which is constructed by joining the two ends of a length of rope using a Double Fisherman's or a Triple Fisherman's.

The Klemheist
The Klemheist
Uses: Its principal use is allowing a rope to be climbed. Two Prusik loops are alternately slid up the static rope: a long Prusik loop allows the climber to lift himself using leg power, and a second short Prusik loop is attached to the harness.

The Bachmann Knot
The Bachmann Knot
In rescue work, if a climber has to be pulled up, a Prusik loop can hold a pulley block purchase system on a climbing rope.
Slide and Grip Knots: Because the Prusik is a symmetrical slide and grip knot, it is useful if a load might need to be applied in either direction. For loads which are always applied in the same direction other knots are preferred such as the Klemheist or the Bachmann pictured here.