Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. In clinical psychology, voyeurism is the sexual interest in or practice of spying on people engaged in intimate behaviors, such as undressing, sexual activity, or other activity usually considered to be of a private nature. In popular imagination the term is used in a more general sense to refer to someone who habitually observes others without their knowledge, with no necessary implication of sexual interest.