A short film is a film with a low running time. The Academy of Motion Picture Arts and Sciences defines a short film as "an original motion picture that has a running time of not more than 40 minutes including all credits".^[1] Other film organizations may use different definitions, however; the Academy of Canadian Cinema and Television, for example, currently defines a short film as 45 minutes or less in the case of documentaries, and 59 minutes or less in the case of scripted narrative films.^[2]

In the United States, short films were generally termed short subjects from the 1920s into the 1970s when confined to two 35 mm reels or less, and featurettes for a film of three or four reels. "Short" was an abbreviation for either term.

The increasingly rare industry term "short subject" carries more of an assumption that the film is shown as part of a presentation along with a feature film. Short films are often screened at local, national, or international film festivals and made by independent filmmakers with either a low budget or no budget at all. They are usually funded by one or more film grants, nonprofit organizations, sponsors, or personal funds. Short films are generally used for industry experience and as a platform to showcase talent to secure funding for future projects from private investors, a production company, or film studios. They can also be released with feature films, and can also be included as bonus features on some home video releases.

All films in the beginning of cinema were very short, sometimes running only a minute or less. It was not until the 1910s when films started to get longer than about ten minutes. The first set of films were presented in 1894 and it was through Thomas Edison's device called a kinetoscope. It was made for individual viewing only. Comedy short films were produced in large numbers compared to lengthy features such as D. W. Griffith's 1915 The Birth of a Nation.^{[citation needed]} By the 1920s, a ticket purchased a varied program including a feature and several supporting works from categories such as second feature, short comedy, 4–10 minute cartoon, travelogue, and newsreel.

Short comedies were especially common, 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).

Animated cartoons came principally as short subjects. Virtually all major film production companies had units assigned to develop and produce shorts, and many companies, especially in the silent and very early sound era, produced mostly or only short subjects.

In the 1930s, the distribution system changed in many countries, owing to the Great Depression. Instead of the cinema owner assembling a program of their own choice, the studios sold a package centered on a main and supporting feature, a cartoon and little else. With the rise of the double feature, two-reel shorts went into decline as a commercial category.

The year 1938 proved to be a turning point in the history of film comedies. Hal Roach, for example, had discontinued all short-subject production except Our Gang, which he finally sold to Metro-Goldwyn-Mayer in 1938. The Vitaphone studio, owned by Warner Bros., discontinued its own line of two-reel comedies in 1938; Educational Pictures did as much that same year, owing to its president Earle W. Hammons unsuccessfully entering the feature-film field. With these major comedy producers out of the running, Columbia Pictures actually expanded its own operations and launched a second two-reel-comedy unit in 1938. Columbia and RKO Radio Pictures kept making two-reel comedies into the 1950s.

Theater managers found it easier and more convenient to fit shorter, one-reel (10-minute) subjects into their double-feature programs. In the live-action field, humorist Robert Benchley had been making short comedies since the dawn of sound; his various series for Fox, Vitaphone, MGM, and Paramount ran from 1928 to 1944. MGM's Pete Smith Specialties had been a standard "added attraction" in moviehouse programming since 1935 and lasted through 1955. RKO's Flicker Flashbacks revivals of silent films ran from 1943 to 1956, and Warner Bros.' Joe McDoakes comedies became a regular series in 1946 and lasted until 1956. By and large, however, the movies' one-reel subject of choice was the animated cartoon, produced by Walt Disney, Warner Bros., MGM, Paramount, Walter Lantz, Columbia, and Terrytoons.

One of the movies' oldest short-subject formats was the adventure serial, first established in 1912. A serial generally ran for 12 to 15 chapters, 15 to 20 minutes each. Every episode ended with the hero or heroine trapped in a life-threatening situation; audiences would have to return the following week to see the outcome. These "chapter plays" remained popular through the 1950s, although both Columbia and Republic Pictures were now making them as cheaply as possible, reusing action highlights from older serials and connecting them with a few new scenes showing identically dressed actors. Even after Republic quit making serials in 1955 and Columbia stopped in 1956, faithful audiences supported them and the studios re-released older serials through the mid-1960s. The 1964 revival of Columbia's Batman serial resulted in a media frenzy, spurring a new Batman TV series and a wave of Batman merchandise.

With the rise of television, the commercial live-action short was virtually dead; most studios canceled their live-action series in 1956. Only The Three Stooges continued making two-reel comedies; their last was released in 1959. Short films had become a medium for student, independent, and specialty work.

Cartoon shorts had a longer life, due in part to the implementation of lower-cost limited animation techniques and the rise of television animation, which allowed shorts to have both theatrical runs and a syndication afterlife. Warner Bros., one of the most prolific of the golden era, underwent several reorganizations in the 1960s before exiting the short film business in 1969 (by which point the shorts had been in televised reruns for years). MGM continued Tom and Jerry (first with a series of poorly-received Eastern European shorts by Gene Deitch, then a better-received run by Warner Bros. alumnus Chuck Jones) until 1967, and Woody Woodpecker lasted to 1972; the creative team behind MGM's 1940s and 1950s cartoons formed Hanna-Barbera Productions in 1957, mainly focusing on television. The Pink Panther was the last regular theatrical cartoon short series, having begun in 1964 (and thus having spent its entire existence in the limited animation era) and ended in 1980. By the 1960s, the market for animated shorts had largely shifted to television, with existing theatrical shorts being syndicated to television.

A few animated shorts continue within the mainstream commercial distribution. For instance, Pixar has screened a short along with each of its feature films during its initial theatrical run since 1995 (producing shorts permanently since 2001).^[3] Since Disney acquired Pixar in 2006, Disney has also produced animated shorts since 2007 with the Goofy short How to Hook Up Your Home Theater and produced a series of live-action ones featuring The Muppets for viewing on YouTube as viral videos to promote the 2011 movie of the same name.

In 2009 the horror short film, No Through Road, that would go viral was released, creating analog horror. The short film would spark 3 sequels, creating No Through Road (web series)

DreamWorks Animation often produces a short sequel to include in the special edition video releases of major features, and are typical of a sufficient length to be broadcast as a TV special, a few films from the studio have added theatrical shorts as well.^{[citation needed]} Warner Bros. often includes old shorts from its considerable library, connected only thematically, on the DVD releases of classic WB movies. From 2010–2012, Warner Bros. also released new Looney Tunes shorts before family films.^{[citation needed]}

Shorts International and Magnolia Pictures organize an annual release of Academy Award-nominated short films in theatres across the US, UK, Canada and Mexico throughout February and March.^[4]

Shorts are occasionally broadcast as filler when a feature film or other work does not fit the standard broadcast schedule. ShortsTV was the first television channel dedicated to short films.^{[citation needed]}

However, short films generally rely on film festival exhibition to reach an audience. Such movies can also be distributed via the Internet. Certain websites which encourage the submission of user-created short films, such as YouTube and Vimeo, have attracted large communities of artists and viewers.^{[citation needed]} Sites like Omeleto, FILMSshort, Short of the Week, Short Films Matter, Short Central and some apps showcase curated shorts.^[5]

Short films are a typical first stage for new filmmakers, but professional actors and crews often still choose to create short films as an alternative form of expression.^{[citation needed]} Amateur filmmaking has grown in popularity as equipment has become more accessible.

The lower production costs of short films often mean that short films can cover alternative subject matter as compared to higher budget feature films. Similarly, unconventional filmmaking techniques such as Pixilation or narratives that are told without dialogue, are more often seen in short films than features.

Tropfest claims to be the world's largest short film festival. Tropfest now takes place in Australia (its birthplace), Arabia, the US and elsewhere. Originating in 1993, Tropfest is often credited as being at least partially responsible for the recent popularity of short films internationally.^{[citation needed]} Also Couch Fest Films, part of Shnit Worldwide Filmfestival, claimed to be the world's largest single-day short film festival.^[6]

Among the oldest film festivals dedicated to short films are Clermont-Ferrand International Short Film Festival, France (since 1979), Tampere Film Festival, Finland (since 1969) and International Short Film Festival Oberhausen, Germany (since 1954). All of them are still considered the most important short film festival in the world to date.

• Reel, for an explanation of the historic term "two-reeler"
• List of animated short series
• List of independent short films
• List of short subjects by Hollywood studio
• Micro movie
• Movieola: The Short Film Channel
• Music video
• One-minute film
• Tampere Film Festival
• The Journal of Short Film
• Tropfest

• British Film Institute: "Writing Short Films" by Phil Parker screenonline, website of the British Film Institute