Varistors are voltage-dependent resistors that are designed to protect electronic circuits from voltage surges and spikes. When the voltage exceeds a certain threshold, the resistance of the varistor drops, allowing it to absorb excess energy and protect sensitive components from damage. Varistors are critical in surge protection devices, power supplies, and industrial equipment, where voltage regulation is essential for safety.

Varistors are commonly used in power lines, automotive electronics, and telecommunication systems. For engineers working on high-voltage projects, varistors provide a simple yet effective solution for protecting circuits from unpredictable voltage fluctuations.