$Q$ is a [[Dimensionless|dimensionless]] property of a [[Damped Harmonic Oscillators|Damped Harmonic System]] that describes its resonance behavior.
$\huge
\begin{align}
Q &= \frac{m\omega_{0}}{b} \\
\frac{1}{Q} &= \frac{\Delta \omega}{\omega_{0}}
\end{align}
$
A higher $Q$ factor means the system loses energy slower an with oscillate for longer, while a longer $Q$ factor means the system will oscillate less due to energy loss.