What Are Screensavers For?
Screensavers were originally designed to protect computer monitors from phosphor burn-in. Early CRT monitors, particularly monochrome ones, had problems with the same image being displayed for a long time. The phosphors, used to make the pixels in the display, would glow at a constant rate for such a long period of time that they would actually discolor the glass surface of the CRT. This discoloration would then be visible as a faint image overlaying whatever else was displayed on the monitor. Advances in display technology and the advent of energy-saver monitors have virtually eliminated the need for screensavers. But we still use them