Another Bus Question

Busses were always traditionally used to group together similar instruments so that the overall level could be controlled from a single fader.
 
The classic example is of course the drum kit where you have each kit piece on it's own track. You carefully tweak and adjust the relative levels of each drum and end up with a balanced kit.
 
Then you add  in the guitars & vocals only to find that the whole of the drum kit is way too loud, so rather than adjust each drum individually you direct their output to a buss and control the whole of the drum kit from one fader.
 
Buss functionality has grown a lot more sophisticated since then of course and you can apply Fx at buss level, use them for parallel processing, setting up stems etc.
 
Their use is limited only by your imagination

A couple of uses of buses (in addition to what was posted above) are:
 
1) Resource consumption reduction - If I want to have reverb on all my drums, and I have all my drums routed to a Drums Bus, I can either put a reverb on the Drums Bus and have reverb added to all the drums with only a single instance of that reverb (instead of having 8-9 different instances of the reverb by having the same reverb with the same setting on the track of each drum kit piece).  I save a lot of memory and a lot of repetition, by just adding that single instance of the reverb effect onto a Drums Bus.
 
2.  Parallel Compression - For this, I would have my drum tracks routed to a Drums Bus, then I would create a Para Comp bus into which I would insert a compressor and set it however I wanted, but with the Dry/Wet mix set to 100% wet.  The Para Comp bus would get fed its signal through the use of a Send from the Drums Bus.  I could add another bus, the Drums Master bus, and route the output from both the Drums Bus and the Para Comp bus to go to the new Drums Master bus, which I could then use to raise or lower the entire drums sound with that one fader.  Back to the Drums Bus and the Para Comp bus - I can blend the levels of those 2 buses to have my normal drums signal, and also have whatever volume I wish of 100% wet compressed drums sound, which sounds really really nice.  I control that balance between those 2 buses to get the combo of non-compressed and compressed drums, and through the Drums Master bus I can control the volume of that blended sound through the single fader of the Drums Master bus.
 
The above can be explored through countless videos out there on YouTube, with better explanations, as you can do a lot with buses.
 
I hope the above helps without making your head hurt.  Others in the forum may well have better explanations for you, and certainly seeing some of the freely available techniques will both show you and let you hear the results, which can only help.
 
Bob Bone
 

I'm finding I am using Busses so much more now, and not just for grouping stuff... They give you endless possibilities to be so creative when using various effects... I do much more parallel processing now, not just compression.
 
I've got one project that has more busses than tracks