Thermistor is a resistance thermometer, or a resistor whose resistance is dependent on temperature. The term is a combination of “thermal” and “resistor”. It is made of metallic oxides, pressed into a bead, disk, or cylindrical shape and then encapsulated with an impermeable material such as epoxy or glass. A thermistor does not actually “read” anything, instead the resistance of a thermistor changes with temperature. How much the resistance changes, it depends on the type of material used in the thermistor. The thermistors are used in cars to measure oil and coolant temperatures, and in household appliances such as ovens and refrigerators.