Gain Margin is a measure used in control systems to assess the stability of a system. It indicates how much gain can be increased before the system becomes unstable. A higher gain margin means the system can tolerate more gain before it starts to oscillate or behave unpredictably. In practical terms, gain margin is often expressed in decibels (dB). If a system has a gain margin of 10 dB, it means the gain can increase by a factor of about 3.16 before instability occurs. This concept is crucial for engineers when designing systems to ensure reliable performance under varying conditions.