The PT-100 is a type of temperature sensor known as a resistance temperature detector (RTD). It operates by measuring the change in electrical resistance of a metal, typically platinum, as the temperature varies. The "100" in its name indicates that the sensor has a resistance of 100 ohms at 0 degrees Celsius. PT-100 sensors are widely used in industrial applications due to their accuracy and stability. They can measure temperatures ranging from -200 to 850 degrees Celsius. Common applications include HVAC systems, food processing, and laboratory equipment, where precise temperature control is essential.