Stepper (or step) motors are really cool. They are perfect for automation or any time you need a motor to turn to a specific point, at a specific speed, in a specific direction. And, unlike typical motors, steppers are able to do all of this, and hold their position when they are not moving – The trade off is that they cant move as fast, and you have to power them at full power all the time, but you get total control in return.
The SHT15 is a digital humidity sensor that outputs a fully calibrated humidity reading. And… because what we are measuring is actually relative humidity, and relative humidity being relative to temperature, the SHT15 has a builtin digital thermometer. This makes things much easier to work with than sensors without a thermometer onboard.