This document discusses different types of documentary films and their codes and conventions. It provides the expository documentary "Catfish" as an example, describing its plot and how it uses techniques like voiceover, interviews, and observational footage. It also summarizes the observational documentary "Big Brother" and how it features unscripted real situations among other conventions. Finally, it examines the participatory documentary "Mark Thomas on Coca Cola," noting how the filmmaker interacts directly with subjects using handheld cameras.