Alt+ ↵ Enter allows for a new line when Enter performs another command.

Alt+ Tab ↹ switches between the currently opened windows on most windowing systems, often referred to as alt-tabbing.Alt+ ⇧ Shift switches between language layouts.Alt+ F4 closes the current window (or shuts down the computer if the desktop is in the foreground) on most windowing systems.Ctrl+ Alt+ ← Backspace usually causes the X display server to shut down or to restart, see Control-Alt-Backspace.Alt+ ⌘ Cmd+ Esc (often referred to as ⌘ Cmd+ ⌥ Opt+ Esc.) brings up the Force Quit window in Apple's macOS, see Option key.Ctrl+ Alt+ Delete may restart the computer (its original function) in some operating systems it brings up a task manager - see Control-Alt-Delete.The Alt key is well known as part of the key combinations: The Option key's behaviour in macOS differs slightly from that of the Windows Alt key (it is used as a modifier rather than to access pull-down menus, for example). Alt is used in non-Mac software, such as non-macOS Unix and Windows programs, but in macOS it is always referred as the Option key. As of 2017, the newest Apple keyboards do not contain the Alt label. Since the 1990s Alt has been printed on the Option key ( ⌥ Opt) on most Mac keyboards. The Alt key should not be confused with the Altmode key (sometimes also labelled Alt) on some Teletype and ASCII terminals, which is a synonym for the ASCII escape character. Macintosh keyboards equate the Alt key with the ⌥ Option key, which has its own symbol, similar to that of the ISO standard. This symbol is encoded in Unicode as U+2387 alternative key symbol (⎇). The standardized keyboard symbol for the Alt key, ⎇ (which may be used when the usual Latin lettering “Alt” is not preferred for labeling the key) is given in ISO/IEC 9995-7 as symbol 25, and in ISO 7000 “Graphical symbols for use on equipment” as symbol ISO-7000-2105. Both placements are in accordance with ISO/IEC 9995-2. The key is located on either side of the space bar, but in non-US PC keyboard layouts, rather than a second Alt key, there is an ' Alt Gr' key to the right of the space bar.

The international standard ISO/IEC 9995-2 calls it Alternate key.

For example, simply pressing A will type the letter 'a', but holding down the Alt key while pressing A will cause the computer to perform an Alt+ A function, which varies from program to program. Thus, the Alt key is a modifier key, used in a similar fashion to the Shift key. The Alt key Alt (pronounced / ˈ ɔː l t/ or / ˈ ʌ l t/) on a computer keyboard is used to change (alternate) the function of other pressed keys.

Alt f4 for mac