The DHT11 is a basic, ultra 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). It¡¦s fairly 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.
Compared to the DHT22, this sensor is less precise, less accurate and works in a smaller range of temperature/humidity, but its smaller and less expensive

• Low cost
• 3 to 5V power and I/O
• 2.5mA max current use during conversion (while requesting data)
• Good for 20-80% humidity readings with 5% accuracy
• Good for 0-50¢XC temperature readings ¡Ó2¢XC accuracy
• No more than 1 Hz sampling rate (once every second)
• Body size 15.5mm x 12mm x 5.5mm
• 4 pins with 0.1" spacing