Quick Answer: A thermistor is a temperature-sensitive resistor whose electrical resistance changes predictably as temperature varies—with 3-5% sensitivity per degree Celsius, making it 10× more responsive than RTDs for precision measurement.

What Is a Thermistor? 

The Essential Definition

A thermistor (thermal + resistor) is a passive semiconductor component whose electrical resistance varies significantly and predictably with temperature changes. Unlike standard fixed-value resistors, thermistors exhibit resistance changes of 3-5% per degree Celsius—making them 10 times more sensitive than RTDs (Resistance Temperature Detectors) for precision temperature measurement and control.