What do the letters ABS stand for in automotive braking?

In automotive braking, ABS stands for anti-lock braking system.

ABS is an electronic safety system that prevents a wheel from locking when the driver brakes hard. Wheel-speed sensors monitor rotation, and a control unit rapidly reduces and reapplies brake pressure when it detects an impending lock-up. This lets the tires continue rolling instead of skidding.

Maintaining rolling contact helps the driver preserve steering control during emergency braking, especially on wet, icy, or uneven roads. ABS does not necessarily shorten stopping distances on every surface; on loose gravel or snow, a locked wheel can sometimes stop more quickly, but the driver generally loses directional control.

The system became widely associated with modern cars after Bosch developed an electronic four-wheel ABS with Mercedes-Benz for the 1978 S-Class. Drivers may feel pulsing through the brake pedal when ABS activates, which is normal. ABS is also distinct from traction control: ABS manages braking during deceleration, while traction control limits wheelspin during acceleration.