Voice-over (also known as off-camera or off-stage commentary) is a production technique where a voice—that is not part of the narrative (non-diegetic)—is used in a radio, television production, filmmaking, theatre, or other presentations. The voice-over is read from a script and may be spoken by someone who appears elsewhere in the production or by a specialist voice actor. Synchronous dialogue, where the voice-over is narrating the action that is taking place at the same time, remains the most common technique in voice-overs. Asynchronous, however, is also used in cinema. It is usually prerecorded and placed over the top of a film or video and commonly used in documentaries or news reports to explain information.
Voice-overs are used in video games and on-hold messages, as well as for announcements and information at events and tourist destinations. It may also be read live for events such as award presentations. Voice-over is added in addition to any existing dialogue and is not to be confused with voice acting or the process of replacing dialogue with a translated version, the latter of which is called dubbing or revoicing.