I've encountered from time to time some plugins that allows a threshold and a ratio to be set so that quieter sound can have an even more quieter level (or silenced altogether). Ableton Live actually has one in it's multiband compressor which, IMO, is very intuitive to use.
I'm curious as to when would this typically be used though? Is it most often used as an effect? Is it used to do mixing corrections? How about mastering? Is there any cases in Audio Production that this would be my "go to" signal processor of choice?
How is it most commonly used and what benefit does it provide?