The "critical point test" (aka "scissors test") requires that if any one item fails, nobody should be injured.
A "bend" is a knot that joins two ropes.
A "hitch" is a type of knot that must be tied around another object.
The "whistle test" requires that if all rescuers let go, nobody should be injured.
A Münter is a hitch that is tied onto a carabiner. You can use the Münter as a descent control "device" (aka a "DCD") when lowering a load or rappelling, or you can use it as a belay device which allows you to take in slack while being ready to catch a sudden load.
An advantage of a Münter hitch is you don't need any additional hardware. A disadvantage is it twists the rope. The twisting usually isn't significant if you rappel once or twice, but if you use the Münter repeatedly the twisted rope can become a real pain.
There are several different ways to tie a Münter. In this first method, you fold the rope on itself and then clip the two strands with a carabiner.