Tag questions are short questions which speakers use at the end of a statement. If the intonation of the tag is falling, then the speaker is asking for confirmation of the statement. If it is rising, then the speaker is unsure and is in fact asking a question. There are rules to the formation of tag questions.
'Your name is Paul, isn't it?' is formed by using the verb 'to be' and changing the positive statement to a negative question.
In the classroom
Many learners have problems with the intonation of some tag questions so need practice in this area.