The document discusses the theory and history of documentaries. It explains that documentaries document real events and use techniques like voiceovers and interviews to create meaning and emotional responses for audiences. It introduces John Grierson, considered the father of British documentaries, who coined the term "documentary" and used the form to bring important social issues to viewers. John Corner is also discussed and he identifies key elements of documentaries like observation, interviews, dramatization, and exposition. Finally, different types of documentaries are outlined such as expository, poetic, and observational modes.