LED: The Light Emitting Diode

Lights on highway
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LED stands for light-emitting diode. An LED is a semiconductor that emits light when activated.


  • Traffic signals
  • Street lights
  • TVs
  • Automotive lighting (i.e. brake lights)


  • Reliability: LEDs can (and usually do) last 3 to 5 times as long as traditional bulbs (some are even expected to last 50 times as long).
  • Robust: Because LEDs are solid state (that is, not traditional tubes or bulbs) they are far less likely to suffer failure from damage (think how fragile a bulb is).
  • Size: They can be really, really small so the things they go inside of can be smaller, too.
  • Efficiency: They don't use as much energy as traditional bulbs.


  • Cost: The upfront cost is significantly higher than traditional bulbs. Cost has been coming down steadily and while it might never read parity with traditional bulbs, the fact they last so much longer likely makes up the difference faster than ever.
  • Breadth of light: Simply put, they don't light up a room the way traditional bulbs do. LED's light is more focused (this could be seen as a plus, actually).


Are LED TVs using LEDs?

Despite the name and despite the fact that TVs manufacturers would love for you to think they are (and thus sell you a new TV), LED TVs use the old reliable LCD technology but with an LED backlight. That's why TVs have gotten so thin even in the just the past few years. And because LEDs use less energy, your electricity use won't be as high.