From BlenderWiki

by Someartist

C-Loop Topology

This incomplete head was modeled entirely in Blender from a BOX and it used the C-Loop topology. If you're a beginner I highly recommend that you start with this Loop because it's easy and can save you a lot of stress since you're learning best of all you can create amazing result!

As you can see from the image above, I have gone far and still using that Loop. Now that I understand Topology after using the C-Loop I can branch to other Loops or even invent my own. Here is the Key:

When I look at a wireframe I look for Poles because I can copy the topology using Poles as guide since Pole(s) define a Topology, just look for the Poles. Last, do not be too obsessed with Topologies just read the SUB-D Primer and you'll learn that having a clean/kick-arse Topology doesn't mean it will deform correctly during animation. However for still images/Zbrush sculpting a CLEAN MESH is best. When you get into deformation and things doesn't work out just use the knowledge here to change/adapt which is better than trying to learn all the topologies that exist out there.