Culling

From DeleDWiki

Culling is the process where a polygon - either facing away from the perspective of the 3D camera or hidden from sight - is not rendered. This process makes rendering 3D objects more efficient and quicker, as it reduces the amount of geometry that is rendered on the screen at a given time.

There are several forms of culling in Computer Graphics, Geometry Culling in 3D Engines by Pietari Laurila can give a more complete understanding of the various culling techniques.