The PT100 3-wire Temperature Probe is a type of RTD platinum probe used to measure temperatures up to 250°C. This type of probe can be used with RTD Click Board™.
RTD sensors are basically thermosensitive resistors ' materials that change the resistance depending on their temperature. In this case, the resistor is a small strip of platinum with a resistance of 100' at 0°C - that is why it is called PT100.