Circuitmess Wacky Robot Marv Instructions Manual page 13

The first practical micro
LED was created in 1962
by American engineer
Nicholas Holonyak.
Before that, LEDs didn't have
practical use as they produced
unreliable light or infrared
light that is not visible to us.
The LED made by Holonyak
was the first one that
operated in the visible
spectrum and was red.
LEDs are used to illuminate the
Eiffel Tower every evening.