What is a thermistor ? NTC vs PTC thermistors ?

A thermistor is a resistor where the resistance will change due to temperature ...NTC/PTC - is negative & positive temperature coefficient. NTC are usually used for temperature measurements where PTC can be used for circuit protection, as an increase in temperature results in a increase In resistance, thus can be used as a choke.

Thanks for your kind invitation...

i am not a specialist

This is element that stretch or shrink depend of the temperature , if it is NTC :negative temperature coefficient : it is stretching as the temperature  is going down , and PTC : positive temperature coefficient :stretching as the temperature is going up , Thermistors used for protections purposes