What are Alt Codes ?
On IBM compatible personal computers, characters available in the currently active codepage, but not associated with direct key combinations in the currently active keyboard layout can be entered using the Alt Numpad input method to enter an Alt code: pressing and holding the Alt key while typing the corresponding character code with the keyboard's numeric keypad. Similar or extended forms of this feature are also available in many operating systems, including DOS and Microsoft Windows.
For example hold "Alt" key & press "1" in Num Pad:
Result : ☺