The position of the wheels relative to the car body. Proper wheel alignment reduces tire wear and improves driving control. Normal driving will eventually take wheels slightly out of alignment but running over bumps and curbs will make that happen faster. Cars have adjustments that allow mechanics to bring wheels back in alignment.
A wheel alignment is part of automobile maintenance that consists of adjusting the angles of the wheels so that they are set to the car maker's specification. The purpose of these adjustments is maximum tire life and a vehicle that tracks straight and true when driving along a straight and level road, although most machines and the techs who use them set the alignment to adjust for crowned roads, as well as correct tracking when driving on turns.