A documentary aims to document real events or subjects using techniques like actual footage, reconstructions, and narration. There are several types of documentaries including fully narrated, fly on the wall, mixed, self-reflective, and docudrama. Key features include observation to place the audience as a witness, interviews, gatekeeping of information, mise en scene to compose desired images, exposition to unfold an argument, and use of drama to engage audiences. Documentaries can have open or closed, single or multi-strand, and linear or non-linear narrative structures.