Abstract: Techniques for playing back media files based on their classified emotion classes are disclosed. According to one aspect of the present invention, media files, downloaded or pre-stored, are classified in accordance with a set of emotion classes. Upon receiving a playback instruction from a user, a play-back system (e.g., an audio/video player) is caused to look up one or more of the media files classified in the one of the emotion classes corresponding to the instruction. These selected files are then decoded and played back.