From Jan Tschichold’s Penguin Composition Rules


Put thin spaces (   ) before question marks, exclamation marks, colons and semicolons.

Instead of em ( — ) rules without spaces, use en ( – ) rules preceded and followed by a word space.

Opening quotes should be followed by a hairspace (   ), except when followed by a A and J. Closing quotes should be preceded by a hairspace except after a comma or a full point.


Examples:
Examples :

“Are there any questions?”
“Are there any questions ? ”

What I said was—and it wasn’t new— ‘That is a photograph!’

What I said was – and it wasn’t new – ‘ That is a photograph ! ’ Roots: at the edge of a field