Gikfun 4 Color 10mm Clear LED Light Lamp for Arduino (Pack of 20pcs) EK1045_

In the late 1800s, Thomas Edison invented the first commercially viable light bulb. Light bulbs like this work by passing large amounts of current through a thin filament, which is basically a wire. The filament gets so hot that it starts glowing, and emitting light. This process is very inefficient - less than 5% of the energy going into the bulb gets turned into light - the rest gets turned into heat. A much more efficient source of light is a light emitting diode, or LED. LEDs basically contain two specialized semiconductors that are stuck together, and when you apply a large enough voltage across them, they emit light from a process called electroluminescence. There is some heat produced, but overall the process is a lot more efficient, and you can get a lot of light from a very small device. On average, they last for over 10 years of continuous usage, so you can see why they are po