SRT files are text files that are used in a variety of video playback applications. These files contain the subtitles that are displayed when you play a movie on your computer or on your DVD player.SRT files are commonly used with the DivX and DVD video formats. These SRT files contain the number of the subtitle in the file, the start and end times of when the subtitle appears and up to two lines of the subtitle content. Without the proper SRT files in place, the computer or DVD player is unable to play the subtitles or may play them at the wrong times.