A computer mouse is a pointing device used with GUI (Graphical User Interface) operating systems. It is most frequently used to select an operation
for the computer to perform, select an item from a list, or select a text or graphics area for copy, cut, or paste operations. It can be used for what is known as Drag & Drop
functions. Originaly mice were mechanical, using a spoked mask or wheel to interuppt an LED/photo sensor to detect motion. Modern mice almost exclusively use an LED laser
reflecting off the surface the mouse is moving on to determine direction and distance. There are atleast two buttons mainipulated by the index and midlle finger for selecting
the action the computer is to perform. Some mice have a scroll wheel between the two buttons to cause a text or graphics window to move up or down (scroll).