Zener diode transfers current forward and backward, while traditional diodes are only capable of transferring current forward.

Many different electronic systems use Zener diodes to control their circui's voltage levels.

While there are several ways of doing this, Zener diodes provide efficient voltage regulation without damaging the diode itself.

How Zener Diodes Work
Zener diode acts like a regular diode as current moves in a forward direction in its circuit.

However, when a large enough voltage is applied to the diode in the reverse direction, it travels against the current from the output to the input.

Zener diodes can limit the amount of current that passes through them so that the voltage going backward limits the voltage going forward.

Advantages
Zener diodes are very small and can be integrated into virtually any electronic device, especially small circuits that cannot accommodate other forms of voltage regulation technology.

Zener diodes are also relatively inexpensive and are compatible with most other systems, making them the preferred voltage regulation device.