A documentary film is a nonfictional motion picture intended to document some aspect of reality, primarily for the purposes of instruction, education, or maintaining a historical record. Such films were originally shot on film stock—the only medium available—but now include video and digital productions that can be either direct-to-video, made into a TV show, or released for screening in cinemas. "Documentary" has been described as a "film making practice, a cinematic tradition, and mode of audience reception" that is continually evolving and is without clear boundaries.

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A short film is any motion picture not long enough to be considered a feature film. The Academy of Motion Picture Arts and Sciences defines a short film as "an original motion picture that has a running time of 40 minutes or less, including all credits". In the United States, short films were generally termed Short Subjects from the 1920s into the 1970s when confined to two 35mm reels or less, and featureless for a film of three or four reels. "Short" was an abbreviation for either term.