A Screensaver is a program which gets activated automatically after a computer monitor or a cell phone has been inactive for some time. When it gets activated, it displays a blank screen or moving images. The time duration after which a Screensaver gets automatically activated can be defined by the user. For instance, if the user defines twenty minutes as the time duration, Screensavers get activated the moment there is inactivity for twenty minutes.

Originally, the purpose of a Screensaver, as the name implies, was to save the screen by preventing a fixed display from damaging the screen. Fixed displays would attack the screen at the same places, by virtue of their fixed nature, and would cause damage to those portions of the screen which were under attack. In scientific parlance, this phenomenon is referred to as