Here are a few simple rules about where to place punctuation in sentences with quotation marks. If you’re a writer, this is something you really should know. And if you’re not a writer, this is good for you to know as well because there are a lot of writing snobs out there who think a command of punctuation is directly correlated to one’s IQ. I’m not kidding.
Commas and periods always go INSIDE closing quotation marks. Always, always, always!
(Well, maybe not always. British usage calls for the period outside the closing quotation. But if you’re an American writer, commas and periods always go inside.)
Incorrect: “Altoids”, I said, “are the heroin of breath mints”.
Correct: “Tic-Tacs,” I continued, “are nothing but a gateway mint.”
Colons and semicolons always go OUTSIDE closing quotation marks.
Question marks and exclamation points go OUTSIDE the closing quotation mark unless they are part of what’s quoted.
Correct: My mother is the only person who steps off the plane in Las Vegas and asks, “What time does Jeopardy come on here?”
Correct: Do you agree with the saying, “All’s fair in love and war”?
In the second example, the entire sentence is a question and the quoted material does not pose a question. That’s why the question mark is outside the quotation mark.
Now here’s a tricky one. When you have a question outside quoted material and inside quoted material, use only one question mark and place it INSIDE the quotation mark.
Correct: Did your mother just ask, “What time does Jeopardy come on?”