Well, a sentence can end (properly) with a full stop, an exclamation mark or a question mark. I think that's about it.

Adding to Jessica's answer. Those punctuation marks are important when you read aloud written material. Full stops have long pauses, commas are shorter, question marks indicate that the voice should have a rising inflection. Honouring the punctuation makes a speech easier to understand and more forceful.

a full stop is is form of punctuation meaning the sentence (or thought) is complete. An exclamation point is a full stop but it indicates enthusiasm. Other forms of punctuation indicate a pause. So the thought may not be complete yet or what follows the coma in someway further describes the thought preceeding the coma or modifies it.