Phase Margin is a measure used in control systems and signal processing to assess the stability of a system. It indicates how much additional phase shift can be tolerated before the system becomes unstable. A higher phase margin generally means a more stable system, while a lower phase margin suggests a risk of oscillation or instability. To determine the phase margin, engineers analyze the Bode plot, which displays the system's gain and phase response. The phase margin is calculated at the frequency where the gain crosses 0 dB. This information helps in designing systems that maintain desired performance without becoming unstable.