A film, sometimes also called a movie or cinema, is a cinematographic work of art, which expresses the narration of a story or a fact in a visual audiovisual way, through video or another similar procedure, that is, as a sequence of images (usually accompanied by sound).
In general, a film is based on a script, in which the characters may or may not be played by actors. There is no distinction between the sensitive material in which the images have been printed and the medium in which it is reproduced, such as a movie theater, a television, a computer or a cell phone.
The film industry is the set of companies that produce, distribute, and screen films, and in certain cases also contributing to their dissemination. The sector generates 40 billion dollars in revenue annually. Today, they are an important means of entertainment but they are also used for art expression and education. India creates the highest number of movies in the world.
From the technical point of view, a film is a word of photographic images taken with a camera, and reproduced by a cinematographic projector, using a speed of substitution of images superior to 18 frames per second (traditionally to 24, or in some occasions to 25, even 30 or more like the 48 of the Hobbit) in such a way that creates in the human eye the illusion of continuity, without interruption between each frame due to the retinal persistence.
At first the films were projected without sound, in what is now known as silent cinema, but which years later gave way to sound films, which increased the expressive potential of the films. A film before being completed is mounted with a different soundtrack to the one that will be used definitively, this is called temp track.
With the introduction and improvement of video in recent years, magnetic and digital media are increasingly being used to record movies, especially in the case of films made for television, as well as documentaries, short films and amateur films.