Anti-lock braking systems (ABS) help prevent car wheels from locking up during heavy braking. ABS uses sensors to detect wheel lockup and pumps the brakes 100s of times per second to maintain steering control. The key components are speed sensors, valves to control brake pressure, a pump to apply pressure, and an electronic control unit. ABS is effective at reducing crashes and stopping distances compared to regular brakes, but works best on clean, dry surfaces and may not perform as well on loose surfaces like snow or ice.