Curtis Newbold, a communications professor and self-named “Visual Communication Guy,” has created an infographic ranking the 15 punctuation marks in order of difficulty. On the far left are the humble period, question mark, and exclamation point, with their easy-to-grasp rule. On the far right is, of course, the comma — the punctuation mark that generates the most confusion. Newbold’s graph is also available on his website as a free high-resolution PDF for printing.
Newbold goes more into depth on five of the most confusing marks in the Punctuation Portal of his blog, where he calls punctuation “the visual rhythm of our language.”
Alternatively, the comments section under Newbold’s post, as well as where the infographic is shared on designtaxi.com, is a great example of how passionate the discussion on language and design can be.