Wheel alignment, also called steering geometry, ensures a vehicle's wheels are properly positioned for directional stability, smooth rolling, and safe recovery after turns. It involves adjusting the caster angle, camber, king pin inclination, toe-in and toe-out. A positive caster angle of about 30 improves stability and reduces tire wear, while negative caster has poor stability. Camber is the tilt of wheels from vertical, with positive camber tilting outward at the top. Toe-in and toe-out refer to the front wheels pointing inward or outward when viewed from the top.