Diode
An LED produces light when electricity flows through it.  It is a longer lasting and more efficient way of creating light than incandescent light bulbs. Depending on how it was made, the LED can make different colors. LEDs were first used in the 1970's. The light-emitting diode may eventually replace the light bulb as developing technology makes it brighter and cheaper (it is already more efficient and lasts longer). In the 1970's the LEDs were used to show numbers in appliances such as calculators, and as a way to show the power was on for larger appliances.