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Dialog
Dialog uses dialog tags such as: he screamed, she exclaimed, they chorused. In American English, the majority of writing uses double quotations " " to indicate spoken words.
What to use and when
Never end a quotation with a period if you are going to use a dialog tag after the quotation instead use a comma. If you put the dialog tag first or do not use a dialog tag, then you can end the quotation with a period.