What is true power?

Hint: True power can be defined as the actual power consumed by the equipment to do useful work in an AC circuit. It can be identified from the apparent power by eliminating the reactive component which may be present.

Complete answer:
The true power indicates the power drawn by the circuit’s resistance for doing useful work.
 In the single phase system, the power is expressed as –
$P = VI\cos \phi $
Where $I$ is the rms current
$V$ is the rms Voltage
$\phi $ is the phase shift which is between the voltage and the sinusoidal current and also known as the phase angle.
The true power is measured in watts. In the purely resistive circuit, the angle of measure is zero and the true power is given by VI.
True power is also known as the real power, actual power, useful power or the watt-full power.
The power which is drawn from the mains is the apparent power and is the combination of both the true power and the reactive power. The true power is because of the resistive components while the reactive power is due to the inductive and the capacitive components.

Note:
Know the relationship between the terminologies between the true power, reactive power and the apparent power. Apparent power is measured in VA and the reactive power is measured in VAR.