Which property primarily characterizes a diode's function?

The property that primarily characterizes a diode's function is rectification. Diodes are semiconductor devices that allow current to flow in one direction while blocking it in the opposite direction. This property of allowing current to pass only in one direction is crucial for converting alternating current (AC) to direct current (DC), which is the process known as rectification.

In electronic circuits, diodes are commonly used for tasks like rectifying the output of power supplies and protecting circuits from reverse voltage, making their rectifying capability fundamental to many electronic systems. This characteristic distinguishes diodes from other devices that may amplify signals, conduct current indiscriminately in either direction, or serve insulating purposes.