ESP

ESP or Electronic Stability Program is an extension of the ABS. ESP uses yaw-rate and lateral acceleration sensors to determine actual vehicle behaviour. By also monitoring driver behaviour (usually through a steering-angle sensor), the ESP system can compare the drivers intentions to the vehicles actual behaviour and act upon these comparisons to modify the behaviour of the vehicle.

ABS

ABS or Antilock Braking System is a driver aid common on most modern passenger vehicles. By comparing the individual speed of each wheel, the system can determine whether or not a wheel is starting to slip. At the point where the wheel would break traction and start to "skid", brake force is reduced untill optimum traction is restored, at which point it is re-applied. This continual variation in brake force results in the associated "judder" felt when ABS comes into effect.