Faces
A face is a single Non-uniform Rational B-Spline (NURBS) and is the smallest area entity. It has a separate underlying mathematical definition, specified when it was created.
- plane
 - cylinder/cone
 - sphere
 - torus
 - NURBS
 
A surface can be made up of a single face type or of multiple face types. Multiple types are used for more complex surfaces that contain sharp corners or highly complex shapes.