On Twitter, Brent Spiner (yes Data from Star Trek: The Next Generation) re-tweeted messages about the proper use of the quotation mark.  Now I’m no expert on the proper use of any punctuation mark, but I found an english teacher at Williams College.

The most common grammatical error in your papers is misplacing commas

and periods outside of quotation marks.

Periods go inside quotation marks, as in

Robert Frost is the author of “Design.”

Commas go inside quotation marks, as in

Robert Frost is the author of “Design,” as well as many other poems.

Question marks go outside quotation marks (unless, of course, they are part

of the quotation). As in

Is Robert Frost the author of “Design”?

 

 Hope this clears it up!

Source:Professor Lawrence Raab, Williams College.