The punctuation marks that signal the end of a sentence are the period, the question mark and the exclamation mark.

You use the period, by far the most common of the end punctuation marks, to terminate a sentence that makes a statement. Some countries refer to this punctuation mark as a full point or a full stop. You may also use periods with imperative sentences that have no sense of urgency or excitement attached:

Without a doubt, Lady Emily was much happier after her divorce.

Turn right at the stop sign.

Bring me a cup of coffee and a cheese danish.

When you want to express a sense of urgency or very strong emotion, you may end your imperative sentences and statements with an exclamation mark. Exclamation marks are, however, rare in formal writing. Use them sparingly, if at all.:

Look out below!

Leave this house at once!

I hate him!

You should use the question mark at the end of a direct question:

Who's on first?

Where is my flowered cape?

Be careful not to use a question mark at the end of an indirect question. Indirect questions are simply statements, and therefore end with a period:

I wonder who was chosen as Harvest King in the county fair.

She asked if she could play pinball.

The teacher asked who was chewing gum.