A subdivision surface is a surface that has been divided into more faces while retaining the object's general shape. You perform subdivision to add more detail to an object, or to smooth it out.
You can create a subdivision surface by applying a modifier to an object. Autodesk VIZ supports two kinds of subdivision surfaces:
The HSDS modifier provides hierarchical subdivision surfaces.
The MeshSmooth modifier and TurboSmooth modifier provide smoothing.
Both these modifiers work best as finishing tools for models.
The Interface for an Editable Poly object allows you to add a subdivision surface to this type of object without the use of a modifier.