I often talk about edgeloops, when discussing modeling. An example I often refer to is good or bad knee pads. If the knee pads have bad edgeloops – or too much fabric at the back of the knee, it bunches up and you get bruises.  Good edgeloops, or thinner surface area in the bend gives a nicer bend and is much more comfortable.  Rule #1 in rigging – have good edgeloops in your model.