To comma or not to comma. If you're writing a book, you're going to face this question maybe 100 times...if not more. With each line of dialogue you write comes an important question: am I supposed to end it with a comma or a period?
The End of the Sentence
Punctuating dialogue is one of the most confusing tasks you'll face as an author. You're already introducing quotation marks into the mix, which is extra punctuation, and you can't ignore all the normal rules of the game, either. So every time you write a new line, it's a new challenge.