How to map surface in retopologizing I decided to practice a bit with blender and I was trying to create a head following this tutorial on net:
Creating a Realistic Head in Blender

It is speed up so its hard to sometimes figure out what is going on.
I am now on retopologizing section, however I noticed that when author of the tutorial shows just retopologized part (not yet finished just to check it out) you can see it smoothly with crevasses and such things, it looks as if he somehow mapped surface/geometry of the high poly model he made before to that retopologized model.

My question is how did he do it and how could i do it? My retopologized model just looks like bunch of flat faces. I study art at college and I wanted to go deeper into 3D modelling, our lessons on this subject were rather scarce unfortunately.
What He does is add a sub surf modifier(Ctrl-2), as well as enable smooth shading Tab to enter edit mode, A to select every thing, W>Shade Smooth, and Tab to exit edit mode.