An RTD (Resistance Temperature Detector) is a temperature sensor that measures temperature by correlating the resistance of the sensor element with temperature. Typically made of pure platinum, RTDs are known for their high accuracy, stability, and linear response over a wide temperature range. They are widely used in industrial and scientific applications where precise and reliable temperature measurement is critical. Unlike thermocouples, RTDs require an electrical current to pass through the element to measure the resistance, which changes with temperature.