What is susceptance?

In alternating current circuits, admittance (Y) is the reciprocal of impedance (Z) and measures how easily a circuit allows current to flow. Just like impedance, admittance is a complex number consisting of a real part and an imaginary part. The real part of admittance is called conductance (G), which is the reciprocal of resistance. The imaginary part is called susceptance (B), which is the reciprocal of pure reactance. Distractors that mention magnetic fields or transformer efficiency are designed to sound technical but are completely unrelated. Susceptance is strictly defined as the imaginary component of a circuit's admittance.