A non-fiction film. Pre-production in this case involves intensive research of the topic of the film, ostensibly an interesting or intriguing thesis comprising actual events or facts. The resulting documentary film is a visual record of this research. Consisting often of interviews, bits of evidentary film, pictures many times old historical footage or film of a relevant location.
A documentary normally has a narrative thread similar to a fiction film. Unlike a news report for example a documentary is usually feature film length and employs story development techniques to sustain viewer interest. The first documentary films were already produced in the 19th Century. Simple recordings of steam locomotives or crowd scenes or similar motifs.
Many film historians generally cite the Lumiere Brothers short film, L’ARRIVEE D’UN TRAIN from 1895 as the first documentary film ever made. The film depicts the arrival of a train in a station. Initial audiences, who had never before seen a film, fled the theatre thinking the train so realistic in the film that it would crash through the screen and roll over them in their seats.