What is needed when a written complete thought or idea ends?

A complete thought is called a sentence. The following punctuation marks end different kinds of sentences: (1) period if the sentence is a statement or a command; these are called declarative and imperative sentences, respectively; (2) question mark if the sentence is a question; this is called an interrogatory sentence; and (3) exclamation point if the sentence is an exclamatory sentence. Note that exclamation points are not too precise, and writers can choose to use them with any sentence they want to make loud or forceful. If the loud or forceful sentence is also a question, the exclamation point is followed by a question mark.