Most system housings have a number of indicator, or activity, lights on the chassis. These lights, tiny light-emitting diodes (LEDs), indicate that a certain component is active, such as power into the system, or access of a |disk drive|. Most indicator lights will blink if the activity of the component is intermittent, such as with a hard disk. These lights are particularly helpful in preventing mistakes such as removing a |floppy| from its drive while the computer is still accessing it (which will likely damage the disk).
