A switching diode is a two terminal PN junction, often used in electronic systems to manage small voltages.
A Switching Diode is commonly referred to as a "Signal Diode", it is a semiconductor that can be used to switch signals or act as a rectifier at low voltages.
Within a circuit they can provide similar functionality to a physical switch, with the on/off state governed by the direction of the current flow. When there is forward current in the circuit (forward-bias), the switching diode effectively is a closed switch with low resistance, allowing current to flow. If the current of the circuit is reversed (reverse bias), the switching diode provides high resistance, preventing current flow up to a specified threshold.
A switching diode can be used in low voltage applications that require fast switching and a high speed rectification. A diode can also be used as a circuit protection device to prevent reverse current damaging a device upstream of the switching diode, such as microcontroller.