The Led works under the same principles as the rectifier diode, but the N and P regions are built with special materials that emit a certain wavelength of light when a current flows through them.
The main advantages of the led diode is that it is smaller and uses less current than traditional light bulbs. Their main use is as indicators and lighting for small areas.
Led circuits are very popular among electronics enthusiasts because they can see how their circuit is working, and can also be used to produce a number of very interesting light effects.