Before 1920s, most of films with no synchronized recorded sound, especially with no spoken dialogue. In 1927, the first feature-length motion picture with synchronized dialogue sequences "The Jazz Singer" released, it made a new history of sound film.
A sound film is a motion picture with sunchronized sound, or sound technologically coupled to image, as opposed to a silent film. At the beginning a projected sound-film system know as Cinemacrophonograph or Phonorama, based primarily on the work of Swiss-born inventor François Dussaud, was exhibited in Paris; similar to the Kinetophone, the system required individual use of earphones. However with rapid development of technology, film making with sound is getting better and easier. We call the music of the film as O.S.T (Original Soudtrack).
A soundtrack can be recorded music accompanying and synchronized to the images of a motion picture, book, TV program or video game; a commercially released soundtrack album of music as featured in the soundtrack of a film or TV show; or the physical area of a film that contains the synchronized recorded sound. There are five types of soundtrack recordings. The first is musical film soundtracks which concentrate primarily on the songs such as "Singin' in the Rain". The second is film scores which showcase the background music from non-musicals for example "Star Wars". The third is albums of pop songs heard in whole or part in the background of non-musicals such as "When Harry Met Sally". The fourth is video game soundtracks are often released after a game's release, usually consisting of the background music from the game's levels, menus, title screens, promo material,cut-screens and occasionally sound-effects used in the game. The last one is albums which contain both music and dialogue from the film, such as" The Sound of Music".