Screensavers

Screensavers were first created to protect a computer monitor from phosphor burn-in. Early monitors had problems with the same image being displayed over and over for long periods of time. The phosphors, used to make the pixels in the display, glow at a constant rate for such a long period of time that they could discolor the glass surface of the monitor. This discoloration could be visible as a faint image overlaying whatever else was shown on the screen. Advances in technology and the creation of energy-saver monitors have virtually eliminated the need for screensavers.

Having said that, most of us still use screensavers. The most common reason is for entertainment, they just look good, however, you can also use a screensaver for security. Some screensavers can be set up with a password so you can walk away from computer and know it is safe. That's why it is called screensavers.