What is Zener diode? How is it used as voltage regulator?

Explanation

### Step-by-Step Solution

**Step 1: Definition of Zener Diode**
A Zener diode is a type of semiconductor diode that allows current to flow in the reverse direction when the voltage exceeds a certain value known as the Zener breakdown voltage. Unlike regular diodes, Zener diodes are designed to operate in the breakdown region without being damaged.

**Step 2: Purpose of Zener Diode**
The primary purpose of a Zener diode is to provide voltage regulation. It maintains a constant output voltage despite variations in the input voltage or load current. This is crucial in electronic circuits where a stable voltage is required.

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