A Light Emitting Diode is a solid-state semiconductor device that converts electricity directly into Light. The heart of an LED is a semiconductor wafer, one end of which is attached to a stand, one end is negative and the other end is connected to the positive end of the power supply, so that the entire wafer is encapsulated in epoxy resin. A semiconductor chip is made up of three parts: one is a p-type semiconductor, in which the holes are dominant, the other is an n-type semiconductor, in which the electrons are dominant, and the middle is usually a quantum well of one to five cycles. When a current passes through the wire on the chip, electrons and holes are pushed into a quantum well, where electrons recombine with holes and emit energy as photons, which is how leds glow. And the wavelength of light, the color of the light, is determined by the material that forms the p-n junction.