I got the Elegoo Super Starter Kit for Uno. Along with all the electronic goodies it had some tutorials for the Arduino. Lesson 11, about the DHT11 temperature and humidity sensor, included a pinout diagram and data sheet for the sensor. So far, so good.
When I went to assemble the breadboard I found that my sensor had three pins instead of the four pins shown in the lesson plan and datasheet. The instructions were for a sensor that looked like the one on the top in the image below and the sensor I had looked like the one on the bottom.
DHT11 Pinout for Three-Pin and Four-Pin Types
It took some searching, but I found out that there are two versions of the sensor—the two shown in the image.
I found the pinout diagram for my sensor and I think the way the three-pin version is labeled in the image is correct.