A light-emitting diode (LED) (pronounced /ˌɛliːˈdiː/[1], or just /lɛd/), is an electronic light source. The LED was first invented in Russia in the 1920s, and introduced in America as a practical electronic component in 1962. Oleg Vladimirovich Losev was a radio technician who noticed that diodes used in radio receivers emitted light when current was passed through them. In 1927, he published details in a Russian journal of the first ever LED.[citation needed]
According to wikipedia - http://en.wikipedia.org/wiki/Light-emitting_diode