Münter Hitch
The Münter hitch, also called the Italian hitch, is an important safety knot that every climber should know how to tie and use. The Münter hitch, named for Swiss climber Werner Münter who invented it, is a simple knot used for belaying and rappelling. It’s ideal to use if you lose or forget your rappel/belay device and need to either rappel or belay.
The Münter hitch works by creating friction from several bends in the climbing rope which threads through a carabiner.
It’s best to use a large pear-shaped locking carabiner since the hitch inverts when you either take in or give out rope. The hitch locks on itself when weighted, but pulls when loosened. Only use the knot with a locking carabiner, preferably an auto-locking one, since the action of the knot pulling in the carabiner can cause a screw-gate carabiner to come undone. If you do use a screw-gate, tighten it down and check it often. The knot is easy to tie with practice and works well.
The primary drawback to the Münter hitch is that it kinks and twists the rope. If you use a Münter hitch for rappelling, it’s recommended to use it mostly for short rappels because as the rope runs across itself, it can create excessive friction that could damage the rope’s sheath. To rappel with the Münter hitch, use two separate carabiners, one for each rappel rope strand, to lessen friction.
Source...