Which property of a semiconductor diode permits its use for reverse-polarity protection?

A semiconductor diode acts essentially as a one-way check valve for electricity, allowing current to pass easily in the forward direction but blocking it in the reverse direction. Because of this characteristic, placing a diode in series with a power input will physically block current from flowing if a user accidentally connects the battery or power supply backwards, thus protecting the circuit from damage. Options such as high forward resistance or a low peak inverse voltage are actually undesirable traits for a power diode. The protective capability relies entirely on the fundamental property that a diode conducts in one direction only.