The theater is a performing art . In French , it is commonly referred to as the ” seventh art “, according to the expression of the critic Ricciotto Canudo in the 1920s 1 . The cinematographic art is characterized by the spectacle proposed to the public in the form of a film, that is to say a narrative (fictional or documentary), conveyed by a medium (flexible film, magnetic tape, digital container) which is recorded and read by a continuous or intermittent mechanism that creates the illusion of moving images, or by continuous recording and reading of computer data. Communication to the public of the recorded show, which is different from the live performance, is done by the illumination through the support, the passage of light by a set of mirrors and / or optical lenses, and the projection of this light beam on a transparent screen (Émile Reynaud, Thomas Edison ) or opaque (Lumière brothers), or the diffusion of the digital signal on a plasma or LED screen. In the original and limiting sense, cinema is the public projection of a film on a screen (indoor or outdoor). From Émile Reynaud, in 1892Film creators understand that the projected show is better accompanied by music that builds the mood of the story, or highlights each action represented. Very quickly, they add noises caused by an assistant during each screening, and make comments on the actions by a huckster also present in the room. Since its invention, cinema has become a popular art , entertainment , industry and media . It may also be used for advertising, propaganda , pedagogy or scientific research purposes or as part of a personal and singular artistic practice.