This is a valuable skill for those who find themselves driving manual-shift cars, or borrowing a friend’s. The technique basically involves giving the throttle a quick rev as you downshift, making for better continuity of vehicle and engine speed. What’s great about that? It allows the vehicle to use gears in conjunction with brakes to slow itself down, saving some wear on the brake pads. It does not transfer this wear to the gears if the technique is performed correctly.
To dive deeper on how the operation is performed: Imagine you’re in fourth gear and want to slow down. Depress the clutch, blip the throttle so that the engine speed (RPMs) are where they would be with the car moving at the speed you’re at in one gear lower, shift to third, then release the clutch. For a demonstration, try this YouTube video to see the practice in real time (it all happens rather quickly).