Reactive power is a term highly relevant to AC power systems. It denotes the power that does not amount to useful power. The reactive power is the power used to move the active power to the loads. Active Power is the actual power supplied to the loads.

For illustrating this, let’s take an analogy. Previously milk was distributed in milk bottles by companies. These bottles were taken back from customers and reused for the next day’s distribution. Active power is the milk distributed and reactive power is the bottles in which the active power gets distributed.

To understand the technicalities, we need to consider the three types of power namely apparent power, active power and reactive power.

Active Power	Reactive Power	Apparent Power
Power dissipated by a resistive load (like heaters, kettle etc) is active power	Power absorbed by the load due to the presence of reactive components like inductors and/or resistors	It is the total power dissipated or absorbed in the ac circuit`
P=I2R	Q=I2X	S=I2Z
Active power is never negative	Reactive power can be wither positive or negative	It is the vector sum of active and reactive power

The above given figure is the power triangle relating apparent power with active power and reactive power.