SMIL

SMIL (Synchronized Multimedia Integration Language) is a W3C standard for presenting multimedia presentations. It saves the video and audio as one combined file and the text captions as a separate file. Finally, it creates a .smil file (pronounced "smile file") which tells media players like QuickTime how to combine the two files. When a person loads the .smil file the media player will automatically load the necessary media files and synchronize them.

One advantage of the SMIL format is that it allows assistive technologies to have easy access to the captions of a movie.