There are five central elements to documentaries: observation, which places the audience as eyewitnesses; interviews with interviewees addressing the unseen interviewer; use of drama; careful composition of shots; and unfolding of the argument. Gatekeeping in documentaries involves the selection and rejection of information by producers. Narratives can also be categorized as open or closed based on unanswered questions, single or multi-stranded based on narrative threads, and linear, non-linear, or circular based on chronological order.