A question tag, also called a tag question, is an interrogative fragment added to the end of a declarative or imperative sentence.
A question tag, also called a tag question or tail question, is a grammatical structure in which a declarative statement or an imperative is turned into a question by adding an interrogative fragment (the "tag"). For example, in the sentence "You're John, aren't you?", the statement "You're John" is turned into a question by the tag "aren't you". The term "question tag" is generally preferred by British grammarians, while their American counterparts prefer "tag question".