Screensaver
Software program that becomes activated after the computer has been inactive for a specified amount of time. Screensavers were originally designed to help prevent images or text from being burned into older monitors. The monitors and LCDs used today no longer suffer from this issue and screensavers are commonly used today for entertainment, a method of securely protecting your computer while away, or a method of informing visitors of the computer user's status (e.g. out to lunch).
Also see: Burn in, Video definitions