DHT-11 is a Humidity and Temperature Sensor, which generates calibrated digital output. DHT-11 can be interface with any microcontroller like , , etc. and get instantaneous results. DHT-11 is a low cost humidity and temperature sensor which provides high reliability and long term stability. It uses a capacitive humidity sensor and a thermistor to measure the surrounding air, and outputs a digital signal on the data pin (no analog input pins needed). Its very simple to use, and libraries and sample codes are available for . This module makes is easy to connect the DHT-11 sensor to an or microcontroller as includes the pull up resistor required to use the sensor. Only three connections are required to be made to use the sensor – VCC, GND and Output.