Sound film
The primary steps in the commercialization of sound cinema were taken in the mid- to late 1920s. At first, the sound films which included synchronized dialogue, known as "talking pictures", or "talkies", were exclusively shorts. The earliest feature-length movies with recorded sound included only music and effects. The first feature film originally presented as a talkie was "The Jazz Singer", released in October 1927. A major hit, it was made with Vitaphone, which was at the time the leading brand of sound-on-disc technology. Sound-on-film, however, would soon become the standard for talking pictures.
Optical sound
Optical sound is a means of storing sound recordings on transparent film. Originally developed for military purposes, the technology first saw widespread use in the 1920s as a sound-on-film format for motion pictures. Optical sound eventually superseded all of other sound film technologies until the advent of digital sound became the standard in cinema projection booths. Optical sound has also been used for multitrack recording and for creating effects in some musical synthesizers.