Depending on the selection process, there are two types of interview involved, one is where the interview is the only means of assessing, so here both the knowledge of the subject and the personality traits are covered and the other is the interview following a written test where technical skills are already assessed. In such cases, as Nathrao Sir has highlighted the interview is to determine how good is the fit between the two. The type of questions to be asked varies from introductory question like background, family details, educational profile etc thereafter progress to subtle personality traits through direct/indirect questions and could include stress interview too and finally parting questions like when the candidate can join, opening available places, etc