Three common punctuation marks are the period, the question mark and the exclamation point. These three of the 14 different punctuation marks used in English are commonly used at the end of a sentence, but they also have other uses.
The period is used at the end of declarative sentence that is grammatically complete. Periods are also used after abbreviations. A question mark at the end of a sentence indicates that the statement is a direct question. It should not be used at the end of an indirect question such as, "I asked my sister if she had a date." An exclamation point at the end of sentence expresses emphasis or heightened emotion.