These ropes are very stretchy. This strechiness helps to absorb some of the energy generated in a fall, thereby lessening the forces that would be absorbed by the climber. The stretch of dynamic rope makes it undesirable for rappelling and caving activities. Dynamic ropes have a very thin sheath and abrade quickly. Due to their special properties, dynamic ropes are very expensive.
Static ropes have very low stretch properties.
Design gives static rope high abrasion resistance. Static rope is the best choice for rappeling and ascending activites. Static rope should not be used for lead climbing. UIAA is an international body that tests rope and other climbing equipment. UIAA testing is only preformed on dynamic ropes.