NURBS (Non-Uniform Rational B-Splines) are one geometry type you can use to create 3D curves and surfaces in Maya. The other geometry types that Maya provides are polygon and subdivision surfaces.

• Non-Uniform refers to the parameterization of the curve. Non-Uniform curves allow, among other things, the presence of multi-knots, which are needed to represent Bezier curves.
• Rational refers to the underlying mathematical representation. This property allows NURBS to represent exact conics (such as parabolic curves, circles, and ellipses) in addition to free-form curves.
• B-splines are piecewise polynomial curves (splines) that have a parametric representation.

NURBS are useful for constructing many types of organic 3D forms because of the smooth and minimal nature of the curves they use to construct surfaces. NURBS surface types are widely used in the fields of animation, games, scientific visualization, and industrial design.

The NURBS 3D data type can easily be exported to CAD software applications by exporting the surfaces using the IGES file format. In addition, Maya can import many types of bezier and NURBS data types from many CAD software applications using the Autodesk^® Direct Connect^® translator plug-in.

If your requirements are to use the polygon surface type in your scenes you can initially construct your surfaces using NURBS and then convert them to polygons.