Answer 1

Either a space (the thing between two words), or a tab (the key above your caps lock), or a newline (what you get when pressing enter), and some more exotic stuff like a 'carriage return' (when you press enter on windows you get one of those aswell), a 'vertical tab' (never seen one of those in the wild to be honest), or a 'form feed' (remnant of the 1980s).