Periods
Correct: “Periods always live inside quotation marks.”
Incorrect: "Periods always live outside quotation marks”.
Exclamation Points
Correct: The person shouted, "It's my way or the highway!"
Incorrect: The person shouted, "It's my way or the highway"!
Incorrect: The person shouted, "It's my way or the highway,"!
Question Marks
Question marks can fall inside or outside of quotation marks, depending on what type of quote is used. If the original quote asks a question, the question mark should be inside the quotation marks.
Example: The author asks, "Is it our responsibility to recycle?"
If you are asking a question about a quote, the question mark should be outside the quotation marks.
Example: What is the validity of the statement, "Greenhouse gasses cause global warming"?
Commas
Commas always fall inside a quotation mark.
Colons and Semicolons
Both colons and semicolons fall outside of quotation marks, unless they are a part of the quote.