A documentary film (often described simply as a documentary) is a nonfiction, motion picture intended to "document reality, primarily for instruction, education or maintaining a historical record". The American author and media analyst Bill Nichols has characterized the documentary in terms of "a filmmaking practice, a cinematic tradition, and mode of audience reception [that remains] a practice without clear boundaries".
Research into information gathering, as a behavior, and the sharing of knowledge, as a concept, has noted how documentary movies were preceded by the notable practice of documentary photography. This has involved the use of singular photographs to detail the complex attributes of historical events and continues to a certain degree to this day, with an example being the conflict-related photography achieved by popular figures such as Mathew Brady during the American Civil War. Documentary movies evolved from the creation of singular images in order to convey particular types of information in depth, using film as a medium.
