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). Its 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.
\nCompared 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<\/p>\n

Comes with a 4.7K or 10K resistor, which you will want to use as a pullup from the data pin to VCC.<\/p>\n

Technical Details
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Low cost
\n3 to 5V power and I\/O
\n2.5mA max current use during conversion (while requesting data)
\nGood for 20-80% humidity readings with 5% accuracy
\nGood for 0-50\u00b0C temperature readings \u00b12\u00b0C accuracy
\nNo more than 1 Hz sampling rate (once every second)
\nBody size 15.5mm x 12mm x 5.5mm
\n4 pins with 0.1″ spacing<\/p>\n