I use the above for external lights to come on automatically at sunset and turn off at specified time. It requires your location as the sunset and sunrise change everyday, which makes it a great product. It works with CFL and LED bulbs.
Internally, I have lights with switch to turn them off after 15, 30, 45, or 60 mins (bathroom fans, etc.) and others with motion detection.
The above is a great intro to electrical wiring.
I prefer anything that is not connected to TCP/IP, as WIFI and internet are both dangerous attack vectors. Internet of Devices are dangerous!