Alt key

The Alt key on a IBM PC keyboard is either of two keys located next to Space Bar, used to change the function of a key pressed. The Alt key is a modifier key, it is used in the same fashion as the shift key. For example, simply pressing "A" will type the letter A, but if you hold down either alt key while pressing A, the computer will perform an "Alt-A" function, which varies from program to program.

The Alt key has come to replace the Meta key of the old MIT keyboards.

The Alt key is well known as part of the infamous Ctrl-Alt-Delete key combination, used by Microsoft Windows to bring up the task manager when it inevitably crashes.