Think of a radio tuner; the Q-factor is like the precision of the knob. A high Q-factor means the radio isolates a specific station very sharply, rejecting all other overlapping frequencies, while a low Q-factor would make the radio sound like it is playing multiple stations at once.

In a series RLC circuit, resonance occurs when the inductive reactance $X_L = \omega L$ equals the capacitive reactance $X_C = \frac{1}{\omega C}$. At this resonant frequency, the circuit impedance is purely resistive ($Z = R$), resulting in maximum current. The Q-factor is calculated using the formula $Q = \frac{\omega_0 L}{R}$, where $\omega_0$ is the resonant angular frequency, $L$ is the inductance, and $R$ is the resistance.

Remember that Q-factor is also defined as $\frac{1}{R} \sqrt{\frac{L}{C}}$. If capacitance $C$ were provided instead of frequency, you could use this version of the formula.