There are several types of documentary films that have evolved over time: 1. Expository documentaries use narration to directly address the audience and interpret what they see. This is one of the oldest forms. 2. Observational documentaries became possible in the 1960s as cameras got smaller and less intrusive, allowing filmmakers to record social interactions without interfering. 3. Participatory documentaries involve the filmmaker actively engaging with and asking questions of their subjects. 4. Reflexive documentaries from the 1980s demonstrate awareness of the process of interpreting documentaries and issues of realism. 5. Performative documentaries acknowledge the emotional and subjective aspects of documentaries.