(1) (Pixels Per Inch) The measurement of the resolution of a monitor or scanner. For example, a monitor that is 16 inches wide and displays 1600 pixels across its width would have a resolution of 100 ppi (1600 divided by 16). Also rated as "dots per inch" (see dpi). See dot pitch.
(2) (Points Per Inch, Pulses Per Inch) The measurement of mouse movement.
Learn more about ppi