What role does a diode play in an electrical circuit?

A diode is a semiconductor device that plays a critical role in controlling the direction of current flow within an electrical circuit. The key characteristic of a diode is that it allows current to flow in one direction only, while effectively blocking current in the opposite direction. This unidirectional behavior is essential in various applications such as rectification, where alternating current (AC) is converted to direct current (DC). By ensuring that the current can only pass through in one direction, diodes help protect sensitive components downstream from potential damage caused by reverse current. In this way, diodes serve crucial functions in power supply circuits, signal demodulation, and other electronic applications where managing the flow of electricity is necessary.