DHT22 AM2302 Digital Temperature & Humidity Sensor is a 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).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 ground.
 
Although it uses a single-wire to send data it is not Dallas One Wire compatible! If you want multiple sensors, each one must have its own data pin!