The munter hitch has several uses. The most basic use is for rappelling without a rappel device. The munter hitch should never be used as the primary means of rappelling because it damages the rope, but it is essential to know for emergency situations like when you accidentally lose your rappel device. The munter hitch is also used for belaying a rock climber. It can also be used as a contingency anchor. An interesting characteristic of the munter is that it is reversible. That is, either end can be the brake end.
The munter hitch requires a minimal amount of gear - just a locking carabiner.
The munter hitch imposes a lot of wear on your rope. The sheath will get fuzzy and eventually break if you rappel with the munter hitch too much. It also twists the rope and can lead to tangles.