why r screensavers called screensavers, how do they save the screen ?

In the olden days, if an image was left on a screen for a long time it would burn itself into the phosphors, and you'd see a faint ghost of the image permanently. A screensaver with a moving image prevented that from happening. That problem hasn't been relevant for quite a while, but the name screensavers stuck.

A long time ago, after a certain amount of the computer being idle, the things that were on the screen get fixed to the monitor and it would make the things that were really on the screen hard to see, so somebody invented screensavers to keep the image on the screen moving so it wouldn't become fixed to the screen. Now, it doesn't happen anymore and screensavers are just for fun.

Before the proliferation of LCD screens, most computer screens depended on cathode ray tubes (CRTs). Images on a CRT monitor are generated using electron beams which are emitted from electron guns at the back of the tube, and manipulated by electromagnetic fields to form images line-by-line on the phosphorescent screen many times per second. In some situations the images displayed on the screen constantly change, but in other cases some areas of the screen, or the screen as a whole, change very little (the taskbar in Microsoft Windows, for example). When the same image is displayed on a CRT screen for long periods of time, the properties of the exposed areas of phosphor coating on the inside of the screen gradually and permanently change, eventually leading to a darkened shadow or "ghost" image on the screen. Televisions, oscilloscopes and other devices that use CRTs are all susceptible to phosphor burn-in, as are plasma displays to some extent.

The early CRT or picture tube displays would burn an image of your desktop into the phosphor coating inside the screen. This was due to the fact that the image never changed. Screensavers were used originally to keep this from happening.

Back in the "old days" computer screens tend to burn in if nothing would happen on the computer for a couple of hours. Nowadays, the screen turns itself off (goes to standby) or is turned off by the computer if nothing happens for an extended period of time.

So the word screensaver comes from the "good old days" (late 70's, early 80's, I think).

demonstrate screen-savers were invented in the early eighty's even as people were using mono monitors and astounding hues would weakening the demonstrate screen thats why screensavers were used to holding the monitors of being burned by using astounding hues even as pc is idle. those days screensavers are more suitable seen element fairly then a favor.

Originally, if an image was on the screen for too long, it could "burn" a ghost of the image into the screen permanently. Today we use LCD screens versus CRT so its not so much an issue anymore. Now they are just used for either security or entertainment purposes.

They keep the monitor active, if it stayedon one screen for along period of time then it would burn the image your are looking at in the screen and you will always see it, even if the pc is off.

they prevent burn in on computer monitors..... whereby a static image is 'burned' into the screen so when you're doing something else,it appears there's a ghost of the original opening screen there. this was most prevalent in game machines left hooked up to TVs ala atari and nintendo and on early computer monitors that were CRT (cathode ray tube) monitors...

with old computer monitors not having the image change would burn them into the screen. not a problem with today's technology.