An anti-lock braking system, or ABS (from the German, Antiblockiersystem) is a safety system on motor vehicles which prevents the wheels from locking while braking.
A rotating road wheel allows the driver to maintain steering control under heavy braking, by preventing a locked wheel or skid, and allowing the wheel to continue to forward roll and create lateral control, as directed by driver steering inputs. Disadvantages of the system include increased braking distances under some limited circumstances (ice, snow, gravel, “soft” surfaces), and the creation of a “false sense of security” among drivers who do not understand the operation, and limitations of ABS.
Since it came into widespread use in production cars (with “version 2” in 1978), ABS has made considerable progress. Recent versions not only handle the ABS function itself (i.e. preventing wheel locking under braking), but also electronic control of the front-to-rear bias known as electronic brakeforce distribution (EBD), traction control system (TCS or ASR), an “emergency” brake assist (BA, EBA or HBA), and electronic stability control (ESP, ESC or DSC), amongst others.