A light-emitting diode (LED) is a semiconductor light source. When a light-emitting diode is switched on, electrons are able to recombine with holes within the device, releasing energy in the form of photons. This effect is called electroluminescence and the color of the light (corresponding to the energy of the photon) is determined by the energy band gap of the semiconductor.
Modern versions of LED Lights are available across the visible, ultraviolet, and infrared wavelengths, with very high brightness. The advantages LEDs have over incandescent light sources are lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. However, LEDs powerful enough for room lighting are relatively expensive and require more precise current and heat management than compact fluorescent lamp sources of comparable output.