[1] Subdivision modeling is derived from the idea that as a work is progressed, should the artist want to make their work appear less sharp, or "blocky", each face would be divided up into smaller, more detailed faces (usually into sets of four).
Quadrilateral faces, commonly named "quads", are the fundamental entity in box modeling.
While most applications for three-dimensional art provide abilities for faces up to any size, results are often more predictable and consistent when working with quads.
This is so because if one were to draw an X connecting the corner vertices of a quad, the surface normal is nearly always the same.
However, it is difficult to add high amounts of detail to models created using this technique without practice.