The (IAT) sensor is mounted in the intake system so the tip will be exposed to the air entering the engine

Monitors the temperature of the air entering the engine and sends it to the PCM/ECM in form of resistance, and the way this process works is that the PCM/ECM applies a reference voltage to the sensor then looks at the voltage signal it receives back to calculate air temperature.

The PCM/ECM needs this information to estimate air density so it can balance the air/fuel mixture. Cold air is more dense than hot air, so cold air requires more fuel to maintain the same air/fuel ratio. The PCM/ECM changes air/fuel ratio by changing the length of time that the fuel injectors are open.

The intake air temperature is known as a thermistor

Is a resistance thermometer, whose resistance is dependent on temperature. The (IAT) sensor is a thermistor because it depends on resistance to calculate the air temperature. They are two types of thermistors.

As temperature increases resistance decreases. NTC thermistors are both non linear and linear resistors, which alters their resistance characteristics with temperature.

PTC is a thermistor with a positive coefficient, which means the resistance increases as temperature increases