An extra area around the four sides of a television video image that ensures the image will cover the screen completely. Overscan was developed because early television sets varied widely in how they framed images using their cathode ray tube. Modern televisions are more consistent and typically use 1:1 pixel mapping, yet overscan remains available as a legacy setting on some systems. Overscan is also used on some televisions and computer monitors to compensate for the “bezel” that surrounds the screen and that covers the edges of the viewable area of the screen.
Overscan can be an issue when using a television as a monitor for a computer.