Question tags are mini questions added to the end of sentences in spoken English using an auxiliary or modal verb. There are two main types - negative tags after positive sentences and positive tags after negative sentences. Intonation can indicate whether the tag is seeking agreement or confirmation. Specific cases have tags like "shall we?" after "Let's" and "will you?" after imperatives. Pronouns like "they", "it", and "there" are used in tags depending on the subject of the main clause.