For anyone looking to understand how blender’s rendering works, here is a great talk by John Carmack at this year’s QuakeCon:
Questions like, what’s the difference between cycles and blender internal? what is ambient occlusion, how does it work? What is ray tracing? These are all answered very well, or can be answered from what is taught during this talk 
Hey, thanks for posting this. It’s-------Enlightening. No pun intended.
Cheers
Ohh, I love geeky stuff like this, cheers, will watch later!
Hopefully people will watch this and stop saying “Cycles is more realistic” without having any idea why. Might get people to use BI a little bit more too. I also recommend reading the free YafaRay PDF file, it explains raytracing, photon mapping, etc. along these same lines. Great post! *****
Clearly a sharp speaker, shame he didn’t get to cover his bit on displays due to time limits. I was surprised at how technical the questions were from the crowd. Cheers for posting.