It's a tag question, innit?

Tag questions are a kind of yes-no question used when you want to confirm that something is true. They are formed by attaching a question tag to the end of a declarative sentence. Here is one example:

He is in jail, is he?

Notice that the tag "is he" has the same form as the beginning of a normal yes-no question that you would use if you didn't have any idea about the answer:

Is he in jail?