Today, GaN-based LEDs provide the dominant technology for back-illuminated liquid crystal displays in many mobile phones, tablets, laptops, computer monitors, TV screens, etc. Blue and UV-emitting GaN diode lasers are also used in high-density DVDs, which has advanced the technology for storing music, pictures and movies. Future application may include the use of UV-emitting AlGaN/GaN LEDs for water purification, as UV light destroys the DNA of bacteria, viruses and microorganisms. In countries with insufficient or non-existent electricity grids, the electricity from solar panels stored in batteries during daylight, powers white LEDs at night. There, we witness a direct transition from kerosene lamps to white LEDs.