Tag questions are short questions added to the end of statements. They are used to confirm information, encourage a response, or check understanding. A positive statement is followed by a negative tag question, while a negative statement uses a positive tag. Tag questions are formed using auxiliary verbs like "do", "does", and "did" or modal verbs from the statement. There are some exceptions to typical tag question formation for verbs like "be", imperatives, and expressions involving "have got" or "there is/are". Intonation also affects the meaning conveyed by tag questions.