Expository - The expository documentary aims to inform and educate the audience about a certain subject. Screened material can include original and archive footage, and the camera and crew are usually invisible to the audience. The material is tightly scripted and is usually accompanied by some sort of voice-over narration. Example: Natural History programmes.
Observational - The observational documentary aims for a greater degree of naturalness as it is used to observe someone or something in its natural habitat with minimum disruption. Camera and crew are invisible to the audience here also.
Fly-On-The-Wall - Fly-On-The-Wall documentaries are an extension of the observational mode, it aims to blend into the background as the subjects go about their daily business. Filming is usually done during a lengthy time period and aims to give the audience and unmediated access to the world. Example: Big Brother, I'm A Celebrity Get Me Outta Here.
Interactive/Reflexive - In this mode the filmakers presence is fully acknowledged and maybe even emphasized. The film maker is both the author and character in his or her own movie, often appearing in front of the camera and interacting with others. The film might offer surprises, play with conventions and usually aims to provoke reactions from subjects and audiences. Example: Michael Moore Documentaries.
Poetic - This documentary mode emphasizes on creativity as the film maker may explore the beauty in everyday life.
Drama Documentary - In the absence of archive footage or access to witnesses, the film maker might stage a dramatic reconstruction of events.
Mockumentary - These are fictional films which parody the forms and conventions of documentaries, often for a humorous effect. Example: The Office, Confetti.
Personal - These are often shot on video and genrally feature the maker addressing the camera directly, expounding or sharing his views with the audience.