What is a LED bulb?
LED stands for Light-Emitting Diode. It is assembled into a lamp (sometimes called a light bulb) for use in lighting fixtures.
So What Then is an LED?
Technically speaking an LED is a two-lead semiconductor light source that is a p-n-junction diode. When voltage is applied to the leads, electrons are able to recombine with electron holes releasing energy in the form of photons thus emitting light. The color of the light is determined by the band gap of the semiconductor.