ABS is industry-speak for anti-lock brakes, and the system addresses one of the biggest causes of car crashes.
Before ABS, if you jumped on the brake pedal too hard, the brakes would actually overcome the grip of the car’s tyres and the wheels would stop turning. It’s called brake lock-up. Now, when wheels aren’t turning, physics insists they’ll skid in a straight line, even if the steering wheel is turned.
When that happens, the rest of the car won’t steer either and will simply continue straight ahead, usually into whatever it was that caused you to jump on the brakes in the first place. Why hit the brakes so hard? Unfortunately, it’s the natural, panic response to do so: If some braking is good, more must be better, right?
Anyway, ABS, via a sensor, looks at whether the wheels have stopped turning, even though the rest of the car is still moving. And if it detects brake lock-up, the computer releases the brakes for a split-second – just long enough to get the wheels turning again, and allowing you to steer the car around the kangaroo/pedestrian/stray dog or whatever else it was that caused the panic stop.
Of course, your foot is still firmly on the brake pedal at this point, so the brakes will lock-up again almost immediately, but by looking at the situation several times a second, the ABS can continue to cycle the brake pressure on and off and keep the wheels turning while also allowing the car to slow down as fast as possible. And that gives you have a much better chance of steering around what would otherwise be a crash.
How read about how to brake in an emergency situation.