A thermocouple is a temperature sensor composed of two different metals or alloys, with their ends joined together to form a measurement point. When there is a temperature difference at the junction, it generates a voltage signal known as thermoelectric potential. By measuring this voltage signal, temperature changes can be determined. Thermocouples are known for their fast response, wide temperature range (typically from -200°C to 1800°C), resistance to corrosion, high mechanical strength, and are widely used in industrial and scientific applications for temperature measurement and control.