Typing symbols was a challenge because it depended on the software program.
ASCII codes allow you to open text files in software applications.
ASCII codes are also the reason some inputs (like passwords) are case-sensitive.

You cannot use the numbers across the top of the keyboard for this.
You must use the numeric keypad and withNumber Lockenabled.
Ones without leading zeros are based on the original IBM code.

Those with leading zeroes are based on the original Windows code.
For example, to create an n with a tilde, the alt code isOption+n.
To jump into the majority of these symbols, use the Special Characters window.

To open it, pressCommand+Control+Space, then search for the symbol you want to add and double-click it.
Select theApple Logo>System Preferences>Keyboard.
SelectShow keyboard and emoji viewers in menu bar.

Select theKeyboard Viewericon in the menu bar.
PressOptionto see one set of symbols and special characters.
PressOption+Shiftto see the second set of symbols and special characters.

To insert an accented letter or symbol from the Keyboard Viewer, double-click it.