Function of a thermometer

TemperatureThermometers measure temperature, as opposed to heat. Temperature is an intensive property of matter, whereas heat is an extensive one. The Arctic Ocean has more heat than a boiling teapot of water, even though the latter's temperature is much higher, because extensive properties depend upon the amount of stuff you have. Specifically, thermometers measure temperature, which is the speed of particles. The faster the particles in a substance move, the higher the temperature. Slower moving particles have a lower temperature.