Who can talk about the principle of diode current suppression?

Current suppression diodes are usually connected to places where it is necessary to suppress reverse pulses. For example, diodes are reversely connected to both ends of the relay coil. When the coil current suddenly becomes zero, due to the inductance of the coil, a reverse voltage is inevitably generated to prevent the coil current from suddenly becoming zero. At this time, the diode connected in reverse will be turned on to suppress the voltage. This kind of suppression is often encountered in digital circuits. Because the digital circuit works in the transition between on and off states.