There are several types of documentary films. Fully narrated documentaries use an off-screen narrator to provide context to the visuals and help viewers understand nature documentaries. Fly on the wall documentaries simply record real events without narration or an obvious camera presence, allowing viewers to form their own conclusions like in COPS or Deadliest Catch. Mixed documentaries combine interviews, observations, narration and archive footage to advance a narrative argument. Self-reflective documentaries acknowledge the camera's presence and may include interviews with subjects. Docudramas reenact real events for documentary films like Crime Watch. Docusoaps follow individuals' lives over long periods for shows about occupations or communities such as One Born Every