PFC stands for Power Factor Correction, which is a set of mechanisms built into a power supply circuit to raise the power factor (PF) . The PF is the ratio of real power to apparent power, and the higher the PF, the more efficiently the electrical current is being used. There are two basic types of PFC: passive and active. Passive PFC uses passive filtering to remove harmonics, while active PFC modulates the waveforms to reduce the reactive power. Active PFC is more efficient, lighter, and less bulky than passive PFC, but it is also more complex and expensive. PFC is commonly incorporated into computer power supplies, but it is also used in other industries to reduce the reactive power produced by fluorescent and high bay lighting, arc furnaces, and more.