I think what you're talking about is power factor correction. When an inductive or capacitive load is placed on a AC supply, the current and voltage move out of phase - one will lead or lag the other. This can be corrected by placing an equal and opposite inductance or capacitance across the supply to bring the phase difference back to zero.
This is generally no longer needed in consumer devices, as their design has this correction built in. Modern power meters are also better designed, as an old trick was to deliberately throw your power factor far enough out of phase that the meter gave a low reading.