Anti-Lock Brake systems were introduced to assist drivers in maintaining control of their vehicle during emergency braking in all weather conditions. Especially in rain, snow, ice and slick conditions. Simply stated, The ABS computer senses when a wheel locks up when applying the brake pedal and electronically compensates for it by equalizing the brake pressure to all the wheels, thereby avoiding a skidding and out of control vehicle. If you've never experienced the ABS engaging, the brake pedal will pulsate, the brakes will make unfamiliar and sometimes strange growling noises, but not to fear, the system is doing what it's designed to do.