The DHT22 Digital Temperature and Humidity Sensor Module is a basic, low-cost digital temperature and humidity sensor. It uses a capacitive humidity sensor and a thermistor to measure the surrounding air and spits out a digital signal on the data pin (no analog input pins needed).
 
Its simple to use, but requires careful timing to grab data. The only real downside of this sensor is you can only get new data from it once every 2 seconds, so when using our library, sensor readings can be up to 2 seconds old.
Simply connect the first pin on the left to 3-5V power, the second pin to your data input pin, and the rightmost pin to the ground.
 
Features:
High precision
Capacitive type
Full range temperature compensated
Relative humidity and temperature measurement
Calibrated digital signal
Outstanding long-term stability
Extra components not needed
Long transmission distance
Low power consumption
4 pins packaged and fully interchangeable