LEDs (Light Emitting Diodes) are semiconductor devices that emit light when an electric current is passed through them. LEDs are used in a wide variety of applications, including electronic displays, automotive lighting, and general lighting.
The first LED was created in 1907 by H. J. Round of Marconi Labs. However, it was not until 1962 that the first practical LED was invented by Nick Holonyak Jr., while working at General Electric. The early LEDs were made from materials such as gallium arsenide and silicon carbide, which emitted infrared or red light.
Today, LEDs are made from a variety of materials, such as aluminum gallium arsenide and indium gallium nitride, which allow for the emission of visible light. In addition to their use in electronic displays and lighting applications, LEDs are also used in optical fiber communications and medical imaging.