DHT22/AM2302 Temperature and Humidity sensor module
A DHT22/AM2302 digital temperature and humidity sensor module, as described in the February 2017 "El Cheapo Electronic Modules" article.
If you're using this to build the Altimeter/Weather Station from December 2017, you will need a 1k resistor wired between pins 1 and 2 and a 100nF capacitor wired in series with pin 4; see errata.