What type of diode is commonly used for voltage regulation?

The Zener diode is specifically designed for voltage regulation. It operates in the reverse breakdown region, where it can maintain a constant output voltage across its terminals, despite variations in input voltage or load conditions. This unique characteristic makes it highly effective for protecting circuits from voltage fluctuations by providing a stable reference voltage.

In contrast, a standard diode primarily allows current to flow in one direction and is not intended for voltage regulation. Photodiodes convert light into electrical current and are used primarily in applications involving light detection rather than voltage control. Schottky diodes are notable for their fast switching speed and low forward voltage drop, making them advantageous in high-frequency applications, but they do not serve as voltage regulators. Thus, the Zener diode's ability to regulate voltage under varying conditions makes it the ideal choice for such applications.