Do you know ghouls from goblins and ghosts?
A feature (usually of Graphical User Interfaces) 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.