A question mark is a punctuation symbol used at the end of a sentence to indicate that the sentence is a question. It is shaped like a small hook or curve, and its primary function is to signal to the reader that an inquiry is being made. In English, it is placed directly after the last word of the question, without any space. In addition to its grammatical role, the question mark can also convey uncertainty or curiosity in written communication. It is commonly used in various contexts, including text messages, emails, and academic writing, to prompt further discussion or clarification.