These work a lot like a conversation. There is a general aim and topic of conversation but the interviewer is encouraged to prompt the interviewee to so they can expand and elaborate their answers in a free flowing way.
Semi-structured
This falls between unstructured and structured interview; there is a list of questions but the interviewer can explain questions that have been misunderstood and ask follow up questions where appropriate.
Structured
These are made up of pre-determined set of questions that are in a fixed order. It is basically like a questionnaire conducted face to face or over the phone in real time.
