Light Emitting Diode

A kind of diode that when directly polarized starts glowing. Diodes are semiconductor devices that allow electrical current to flow only in one direction. To “directly polarize” means “connect the diode with the correct polarity”.

LED’s have two terminals, the negative one is called cathode and the positive one is called anode.

On computers and electronic appliances LED’s are usually used to indicate that the equipment is turned on. The light (usually green) that indicates that the computer is turned on and the other light (usually red) that indicates that the hard disk drive is being accessed are produced by LED’s, for example.

LED’s can be found in several shapes, sizes and colors.