dpi - technical definition

(Dots Per Inch) The measurement of the resolution of display and printing systems. A typical CRT screen provides 96 dpi, which provides 9,216 dots per square inch (96x96). Flat panel displays from 110 to 200 dpi have also been developed.

Double the DPI, Quadruple the Dots
As the dpi rate doubles, the number of dots within a square inch is quadrupled, because dpi deals with two dimensions. Thus, while 100 dpi produces 10,000 actual dots per square inch, 200 dpi produces 40,000 (see below). We have a long way to go to make the resolution on a screen as dense as a printer. A 1200 dpi printer produces 157 times as many dots of resolution as a typical 96 dpi screen. See dot pitch.

                 Dots Per
      DPI        Square Inch
       96            9,216
      100           10,000
      200           40,000
      300           90,000
      600          360,000
     1200        1,440,000