Voice-Over

Voice-over (marked V.O. in a screenplay) is speech heard over the picture from a source not physically present in the scene, such as a narrator or a character's inner thoughts. It differs from O.S. (off-screen), where the speaker is present in the scene but not visible.

Used well, voice-over adds perspective, irony, or intimacy. Used as a crutch, it explains what the images should show, a frequent target of coverage notes.