Light-Emitting Diodes is a type of semiconductor diode that emits incoherent narrow-spectrum light when electrically biased in the forward direction of the p-n junction, as in the common LED circuit. This effect is a form of electroluminescence. In signage we use LED signs inside letters for face lighting and also halo lighting. By comparison to neon lighting, the benefits of LED's are: it is more energy efficient, it has a longer life, practically no maintenance and the power supply is remotely mounted.