LEDs (light-emitting diodes) are diodes that emit light when a current passes through them. Well on the way to completely replacing filament light bulbs in almost all applications, they can be used as indicators and, with the very high brightness types of LED, can provide illumination.
They are much more efficient than conventional light bulbs, producing far more light per watt of power, and are a lot less delicate.
LEDs do, however, require a little more thought when used. They have to be powered with the correct polarity and require circuitry to limit the current flowing through them.
How to Stop an LED from Burning Out
LEDs are delicate little things and quite easy to destroy accidentally. One of the quickest ways of destroying an LED ...

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