NURBS are Non-Uniform Rational B-Splines. They are a class of geometry that is easily manipulated by computers, allowing for a great deal of flexibility in modeling. They let you create smooth curves and surfaces with only a small number of points.
NURBS curves cannot be rendered, but they can be used to build renderable surfaces, define motion paths, control deformations, and so on. Curves are described in more detail in Curves.
Surfaces are one of the basic types of renderable geometry in Softimage. Surfaces can model precise shapes using less geometry than polygon meshes and they're ideal for smooth, manufactured objects like car and aeroplane bodies. Surfaces are described in more detail in Surfaces.
Surfaces are also the building blocks of surface meshes. Surface meshes provide a way to assemble multiple surfaces into a single object that remains seamless under animation and deformation. They are quilts of surfaces joined at their boundaries, just as polygon meshes are quilts of polygons joined at their edges. Surface meshes are described in more detail in Surface Meshes.
NURBS curves and surfaces share many basic concepts, such as degree, continuity, and parameterization.
