In addition to relevant questions that are typically about drug use and undetected major crimes, the procedure usually includes what are known as "control" questions -- ones that the examinee is secretly expected to answer dishonestly. There are also irrelevant questions, which are not scored. For an example of the kinds of questions typically asked, see the message thread, LAPD Polygraph Questions Disclosed. And for an understanding of the rationale for the various types of questions asked, see Chapter 3 of The Lie Behind the Lie Detector (1 mb PDF).