Still don't understand loop versus ring.

https://blender.stackexchange.com/questions/11038/what-is-the-difference-between-an-edge-loop-and-an-edge-ring

explains the difference with an example. However, I still don't understand how sometimes (or always?) rings and loops are at right angles to each other. Also, do loops and rings only refer to edges, or can they refer to sets of vertices and faces also?