composintg tutorial on the effects that it does

there is a lot of composting tutorials out there, I know so far the difference between color correction and color grading in composting, now that’s far as my knowledge goes besides you need to have render layers and or render passes and as for that goes,are those two layers the same or opposite? I know there is beauty pass layer and adding ambient occlusion, rim light, key light, but then, then there is render layers to save time and memory on rendering out your scene and tutorials on those render layers, are these to combined for composting to cause effects or do they mean make a single render layer of an effect such as ambient occlusion, normal, specular maps and so on and if this is so, why would we have nodes then for these effects in our lighting and texture nodes if these control certain effects to mesh or scene? a lot of tutorials on this subject go over adding 3d mesh and vfx to real footage. but not these layers for composting and if they do, it seems people do what they like and personal choice so you wont hear about certain styles or what composting fully contains and what you need.

I can’t find any tutorials on how they do composting for animation films, I mean is a bloom effect the same thing as a color grade or is it another way to do a volume lighting effect ? and how does cg lighting such as warm and cool color lighting effect or help in composting?

I think this would help me better understand composting since I understand what rendering is, modeling, animation and lighting types there are but not for composting in my case in learning 3d graphics.

Any PDF Compositing tutorials out there?

I really can’t afford to watch a long tutorial, 'cos I miss what they say and forget what they meant and can’t remember half of it the next day.