A tag question is a question converted from a statement by an appended interrogative. It comes in the format of _statement + tag_. Example: "You love me, don't you?" If your question is about a sentence similar to this example, use this tag. (Note: If you have a question, but it's about something else, do not use this tag.)
A tag question, also called tail question or question tag, turns a statement into a question by appending a tag onto the statement. Example:
It is cold today, isn't it?
You saw her yesterday, didn't you?
English has a variety of patterns for tag questions to occur. If your question is about sentences of such structures, you should use this tag. Learners might also ask about intonation and punctuation about tag questions. Such questions as "Should I say 'You are John, aren't you?' in a rising or falling tone?" fall under this category.