Heel-and-toe is a driving technique used in performance driving. It involves operating the accelerator and brake pedals simultaneously with the right foot, and has the purpose of freeing the left foot for normal activation of the clutch or double declutching while downshifting.
Heel-and-toe is usually used before entry into a turn while a vehicle is under braking to prepare for the transmission to be in the optimal gear to accelerate the vehicle out of the turn. Another benefit of downshifting *before* entering a turn is that if one makes a mistake and doesn't get the revs matched correctly, the jolt to the drivetrain won't upset the vehicle as badly if it's still going in a straight line; the same jolt while turning may upset the vehicle enough to cause a nasty spin.
Performance vehicles are usually modified (if necessary) so that the heights of the brake and accelerator pedals are closely matched to permit easy use of heel-and-toe, and that the pedals are not too far apart.
The name, stemming from earlier automotive designs where the accelerator pedal was on the left and could be actuated with the heel while the brake pedal was actuated with the toe, is misleading regarding how the technique is carried out in modern cars, i.e., operating the brake with the left edge of the foot, while rocking it down and to the right to operate the throttle. With practice, it becomes possible to smoothly and independently operate both pedals with one foot. The technique is common in all forms of motorsport, especially rallying.
An unrelated technique, called left-foot braking should not be confused with heel-and-toe.