From time to time, Michael is asked to explain some technical details about NURBS. I think his clarification is always very "digestible". However, you can visit this website and download DesignMentor app (along with DLL libraries) if you want to demonstrate specific terms more graphically yourself. This learning tool allows you to draw varied kind of spline curves, change curve properties, convert curve from one type to another, show radius of curvature, see where internal segments (spans) of curve meet, etc.
Well, there is no need to know how NURBS works to run 3D apps, but it could help if you are interested in...

Petr