Rectangular Light emitting diodes, commonly called Rectangular LED, is widely used in the electronics world. They do dozens of different jobs and are found in all kinds of devices. It is solid semiconductor which is able to transferred electrical energy into visible lighting. The core of the LED is semiconductor crystals, which consist by a P semiconductor and an N semiconductor, thus form a p-n junction. This semiconductor could lighting up when it power on. Among other things, the application range form the numbers on digital clocks, transmit information from remote controls, light up watches and tell you when your appliances are turned on. Collected together, they can form images on a jumbo television screen or illuminate a traffic light. Basically, LED is just tiny light bulbs that fit easily into an electrical circuit. But unlike ordinary incandescent bulbs, they don't have a filament that will burn out, and they don't get especially hot. They are illuminated solely by the movement of electrons in a semiconductor material, and they last just as long as a standard transistor.