- Use a period after a declarative or imperative statement:
I went to the library.
Sign your name here.
- Use a question mark after a direct question or to indicate uncertainty:
What is your name?
Chaucer's dates are 1340?–1400.
Do not use a question mark after an indirect question: I asked them what time they were leaving.
- Use an exclamation point after an exclamatory or emphatic sentence or an interjection:
Give me a break!
Hey! Ouch! Wow!
See also: Period, Question Mark, Exclamation Mark: The End of the Line