An LED will be turned on according to your place's luminosity. It is basically performed through a Light Dependent Resistor (LDR). It is an Arduino project.
It is a very simple project which happens to be my first in Arduino. Basically, you have a tactile switch that will activate (turn on) the circuit or deactivate (turn off). Both operations are performed simply by pressing it. This operation will turn on or off the power led. This led represents when the circuit is ON or OFF.
Once it is activated, it will turn on a second led whenever the LDR (Light Dependent Resistor) realises it is too dark in the room. The threshold (the value which right after it, it is considered DARK) might have to be changed according to your place's luminosity.
I'm a beginner in electronics, and even though I understand this isn't a complex project I hope you enjoy my efforts!