A vehicle's grille is almost always an opening in the front designed to let enough air in to pass by the vents of the Radiator, which is necessary to cool the engine. Some vehicles only use vents (often the case in rear-engine and mid-engine vehicles) for this purpose, and air-cooled engines don't have a radiator, but still use air from the grille for cooling purposes.

The position of the grille in relation to the front bumper can affect how much air gets through it, as well as how much mesh material it consists of and its angle.