1. What is SSS in 3d content
SSS means Subsurface Scattering, it is the way light reacts when going into an object.
the light bounces around a bit before going back out of the surface. this can be demonstrated when you put your hand up to a flashlight, the reddish glowing flesh is where SSS is occuring.
here is a good SSS tutorial:
2. What is GI?
oops, it is actually "Global Illumination", it is the effect when light bounces off of other objects, further illuminating the scene, and it gives a more accurate result.
here is a good GI tutorial:
3. What is CG?
CG means Computer Graphic, so everything you make on a computer is CG....
you might also hear CGI or computer generated imaging.
infortunately, i couldn't find a good tutorial for CG
4. What is HDRI?
HDRI is High Dynamic Range Imagery. Basically. they are images that hold light information along with color. Regular images just hold color, so HDRI is very useful.
you may also hear HDR, they are the same thing.
this tutorial: http://highend3d.com/maya/tutorials/...ray/241-1.html
walks you through using HDRI very well(and does some other cool stuff too)
if you need a better explanation, just ask