Screen Saver - PC's
A background process that monitors system activity such as mouse clicks and key strokes and takes over the system during prolonged periods of idle activity to cover the screen with a display that will prevent damage to its phosphors either by reducing the
intensity of electron flow or by displaying an image that changes
often enough to avoid screen "burn-in". Some screen savers also offer a security option by requiring a password before a user can regain control of the system.