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Sometimes written as two words, as in screen savers, screensavers are computer programs that either blank the screen or, more often, fill the screen with various images or patterns after the computer has been idle for a specified amount of time.

Early computer monitors were based on cathode ray tubes (CRTs), and when the same image was displayed on a CRT screen for a long period, a ghost image would be permanently etched onto the screen, also known as a screen burn-in, due to the properties of the phosphor coating on the inside of the computer screen. To a lesser extent, plasma screens are prone to a similar effect.

Screensavers were developed to avoid these effects by automatically changing the screen during periods of inactivity.

Later CRT technologies reduced the susceptibility of the screens to burn-in, and the LCD screens most commonly in use today are not susceptible to this effect, although a less noticeable and usually temporary form of image persistence may occur.

Although modern computer screens are not susceptible to burn-in, screensavers are still in use, largely for entertainment or decorative purposes. Screensavers usually feature frequently changing photographs or moving images or patterns, such as a simulated aquarium with swimming fish or alternating nature photos.

Since screensavers are intended to activate when the user is away from the computer, many of them can be configured to require a password before the user can resume work on the machine, as a security measure against another person accessing the machine while the user is away.

Some screensavers activate a useful background task, such as a distributed computing application like the SETI@Home project or a virus scan.

Most operating systems include screensaver functions, and third-party applications are available for most OS platforms.

A computer monitor running a screensaver will use roughly the same amount of power as when it is running normally, and using a screensaver with an LCD or flat-panel screen may decrease the lifetime of the display since the backlight remains lit and will age faster than if the screen were turned off and on periodically. Typically, an LCD screen loses about half of its brightness during the product lifetime. Thus, screensavers do not actually save the screen, as the best way to save the screen and reduce the amount of electricity used is to have the computer turn off the monitor when not in use. Nevertheless, screensavers can be fun, and a large percentage of computer users will make use of them.

Topics related to the software powering screensavers are the focus of this category.

 

 

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