A documentary is a non fictional motion picture intended to document some aspect of reality for maintaining a history record. A documentary stands out from the other types of non-fiction films for providing an opinion, and a specific message, along with the facts it presents. The viewer when he sees a documentary inform himself or herself on a subject it is sometimes a learning device withe images. A documentary has a narrator or narration style. Films documentary without word has been made. In 1982 The Quatsi trilogy and Baraka could be described as a visual tone poem style with music related images without a word spoken. Those are the modern documentary.
In the 1950’s to 1970’s Cinéma vérité was born. it was independent film making , they used handheld cameras an a small crew just like the French New Wave and synchronized sound to film events on location as they unfolded. The style include following a person during a crisis with a moving, often handheld, camera to capture more personal reactions. They had a no sit down interview with the subject. Some of the most famous documentary are les raquetteurs and salesman. There is also documentary that are fiction were the film maker fictionalize a story and makes in a documentary. I watched some documentary in my days and will put them on this site from time to time.