A limited-slip differential (LSD) is a type of differential gear train that for on-road use still allows its two output shafts to rotate at different speeds, but limits the maximum difference between the two shafts to enforce a minimum of traction, unlike the common open differential, that allows one wheel to stand still while all power is wasted at the other wheel spinning at double speed, or a locking differential that simply locks them together, mostly temporarily in off-road use.