Tag Questions

You speak English, don't you?

A tag question is a special construction in English. It is a statement followed by a mini-question. The whole sentence is a "tag question", and the mini-question at the end is called a "question tag".

A "tag" is something small that we add to something larger. For example, the little piece of cloth added to a shirt showing size or washing instructions is a tag.
We use tag questions at the end of statements to ask for confirmation. They mean something like: "Am I right?" or "Do you agree?" They are very common in English
Here are some mixed examples:

But you don't really love her, do you?
This will work, won't it?
Well, I couldn't help it, could I?
But you'll tell me if she calls, won't you?
We'd never have known, would we?
The weather's bad, isn't it?
You won't be late, will you?
Nobody knows, do they?