Two-reeler

A short film is any film not long enough to be considered a feature film. Although no consensus exists as to where that boundary is drawn, 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". The term featurette originally applied to a film longer than a short subject, but shorter than a standard feature film.

The increasingly rare term "short subject" means approximately the same thing. It is an industry term which carries more of an assumption that the film is shown as part of a presentation along with a feature film. Short is an abbreviation for either term. Short films are often screened at local, national, or international film festivals and made by independent filmmakers for non profit, either with a low budget or no budget at all. They are usually funded by film grants, non profit organizations, sponsor, or personal funds. Short films are generally used by filmmakers to gain experience and/or prove their talent in order to gain funding for future films from private investors, entertainment companies, or film studios.

Longer and shorter films coexisted with similar popularity throughout the early days of film. However, comedy short films were produced in large numbers compared to lengthy features such as D.W. Griffith's The Birth of a Nation. By the 1920s, a ticket purchased a varied program including a feature and several supporting works from categories such as second feature, short comedy, 5–10 minute cartoon, travelogue and newsreel.

Short comedies were especially popular, and typically came in a serial or series (such as the Our Gang movies, or the many outings of Charlie Chaplin's Little Tramp character). Even though there was often no set release schedule, these series could be considered somewhat like a modern TV sitcom – lower in status than feature films but nevertheless very popular (comedians such as Laurel and Hardy, Charlie Chaplin and Buster Keaton all 'graduated' from shorts to features).

...
Wikipedia