LED stands for Light Emitting Diode. As the current passes through a LED, it emits light. In LED, there is a semiconductor chip, which is made up of N-Type semiconductor layer and P-Type semiconductor layer. There is an active region in between N-type and P-type layer where electrons and holes combine. By applying the forward voltage, electrons of the N-type layer combine with the holes of the P-type layer, to release energy in the form of photons. The color of the emission of light in LED is determined by the energy required by the electrons to cross the band gap of the semiconductor.