ABS=Anti Lock Braking System. When a vehicle goes into a panic stop mode, excessive brake pedal pressure causes the brakes to lock which creates skidding. This effect also takes place in wet, icy or slippery conditions. Consequently, you lose both braking and steering control of the vehicle. To offset these results, pumping the brake pedal reduces the chances of lock-up. OK, now to explain "HOW" it works. Each wheel is equipped with a sensor that's connected to the ABS computer. When you go into a braking situation (Panic or slippage) where the wheel is about to lock, the sensor detects it. This is called "impending lock-up." At this point, the ABS computer activates the ABS mechanism which pumps the brakes for you. This can be as few as 8-10 pumps per second to a rate much higher. That depends upon how violently you step on the brake. Although your foot pedal is steady, the brakes are automatically pumped to prevent lock up and skidding.