Left-foot braking is the technique of using the left foot to operate the brake pedal in an automobile, leaving the right foot dedicated to the throttle pedal.[1] It contrasts with the practice of using the left foot to operate the clutch pedal, leaving the right foot to share the duties of controlling both brake and gas pedals.
At its most basic purpose, left-foot braking can be used to decrease the time spent moving the right foot between the brake and throttle pedals, and can also be used to control load transfer.[1]
It is most commonly used in auto racing(simultaneous gas and brake keeps turbo pressure and reduces turbo lag.