LED string light is made by a lot of LEDS.LED (Light Emitting Diode), a light-emitting diode, is a solid-state semiconductor device that directly converts electricity into light. The heart of LED is a semiconductor chip, one end of the chip attached to a bracket, one end is negative, the other end connected to the positive power supply, so that the entire chip is encapsulated by epoxy resin. The semiconductor wafer is made up of two parts, one part is a P-type semiconductor, in which holes are dominant and the other end is an N-type semiconductor, mostly electrons here. However, when the two semiconductors are connected, a "P-N junction" is formed between them. When a current is applied to the wafer through the wire, the electrons are pushed into the P region, where the electrons recombine with the holes and then emit energy in the form of photons, which is why the LED emits light. The wavelength of light determines the color of light is determined by the formation of P-N junction material.