One of the keys to understanding automated lighting, or any lighting, for that matter, is to follow the flow of energy from the input to the output. A fundamental law of nature is that energy can be neither created nor destroyed; it can only change forms. Electricity is one form of energy, and the job of any lighting system is to take electrical energy and efficiently convert it to light energy. In the real world, only a fraction of the energy put into a lighting system comes out as visible light. Most is lost to heat, some is lost to mechanical energy, and some is converted to invisible light waves.