How does a Zener diode work as a voltage regulator?

A Zener diode operates in reverse breakdown region where it maintains a nearly constant voltage (Zener voltage) across it regardless of current variations within rated limits. In a simple regulator circuit, the Zener is connected in parallel with the load through a series resistor. When input voltage increases, the Zener conducts more current while maintaining constant output voltage. It is simple but suitable only for low-power applications due to power dissipation.