Screensavers are applications that run automatically after a set period of inactive computer usage. It all began with the stars screensaver in Windows 3.1 and has evolved into ribbons of light that bend across the screen. Screensavers can be made up of literally anything. Picture slideshows, movies, music playlists, flying toasters and more. Another great use for screensavers is that they can automatically activate while you are away from your computer and when you return, a password will have activated, if you so choose.