Traditional films are made up of a series of individual images called frames. When these images are shown rapidly in succession, a viewer has the illusion that motion is occurring. The viewer cannot see the flickering between frames due to an effect known as persistence of vision, whereby the eye retains a visual image for a fraction of a second after the source has been removed. Viewers perceive motion due to a psychological effect called beta movement.
Film critics working for newspapers, magazines, and broadcast media mainly review new releases. Normally they only see any given film once and have only a day or two to formulate opinions. Despite this, critics have an important impact on films, especially those of certain genres. Mass marketed action, horror, and comedy films tend not to be greatly affected by a critic's overall judgment of a film.
The origin of the name "film" comes from the fact that photographic film (also called film stock) has historically been the primary medium for recording and displaying motion pictures. Many other terms exist for an individual motion picture, including picture, picture show, photo-play, flick, and most commonly, movie. Additional terms for the field in general include the big screen, the silver screen, the cinema, and the movies.
