Source : Free On-Line Dictionary of Computing

mouse trails
     
         A feature (usually of {Graphical User
        Interface}s) which causes the {mouse} {pointer} to leave a
        trail across the screen.  This is done by keeping track of the
        last eight or so (maybe configurable) pointer positions, and
        only erasing the oldest.  This means that at any time, there
        may be up to eight pointers on the screen, but if the mouse is
        still, they will all be in the same position, and so only one
        will be visible.  When the mouse moves, it appears to leave a
        trail of pointers behind it, and this can dramatically
        increase the visibility of the pointer when using {LCD}
        screens.  The older ones had such long {persistence} that a
        single mouse pointer, when moving, tended to be completely
        invisible, and on a cluttered screen, was very difficult to
        find.
     
        (1996-07-08)