PFC (power factor correction or power factor controller)

PFC (power factor correction; also known as power factor controller) is a feature included in some computer and other Power Supply boxes that reduces the amount of reactive power generated by a computer. Reactive power operates at right angles to true power and energizes the magnetic field. Reactive power has no real value for an electronic device, but electric companies charge for both true and reactive power resulting in unnecessary charges. PFC is a required feature for Power Supplies shipped to Europe.