LEDs, or light–emitting diodes, are semiconductor devices that produce visible light when an electrical current passed through them. LEDs are a type of Solid State Lighting (SSL), as are organic light–emitting diodes (OLEDs) and light–emitting polymers (LEPs).
LED lighting products use light emitting diodes to produce light very efficiently. Also, LEDs are “directional” light sources, which mean they emit light in a specific direction, unlike incandescent and compact fluorescent bulbs, which emit light and heat in all directions.