Explanation

"If your car is fitted with an anti-lock braking system (ABS), this will activate when you brake so hard that the tyres start to lose their grip on the road surface. At this point, the wheels would normally lock up and a skid would start. The ABS senses the wheel locking and releases the brake pressure just enough to avoid the skid. It then cycles through applying and releasing the brake pressure many times per second. This ensures maximum braking for the available grip is constantly applied without the wheels locking."