זה לא סתם כפתור ALT, הוא עובד קצת שונה, אז למה הוא בעצם משמש?

http://en.wikipedia.org/wiki/AltGr_key

AltGr is a modifier key on PC keyboards used to type many characters, primarily ones that are unusual for the locale of the keyboard layout, such as currency symbols and accented letters.

If a key has a third symbol on it (on the front vertical face or the bottom right of the key top, sometimes in a different colour), then AltGr can often be used to type that character. It is also most commonly used for BIOS settings.

מובן, תודה