The document discusses various types of power in AC circuits including active power, reactive power, apparent power and power factor. It defines these terms and discusses how to calculate them. Reactive power is caused by inductive or capacitive loads. Apparent power is the total power and accounts for both active and reactive power. Power factor is the ratio of active to apparent power and indicates how efficiently current is being used in a circuit. Power factor correction can be used to improve efficiency by adding capacitors to counteract the effects of inductive loads.