Dot pitch, or "pixel pitch," is a measurement that defines the sharpness of a monitor's display. It measures the distance between the dots that display the image on the screen. This distance is very small and is typically measured in fractions of millimeters. The smaller the dot pitch, the sharper the picture.
Dot pitch applies to both CRT monitors and flat-screen displays. While some large-screen CRTs have dot-pitches as high as .51 mm, most computer displays have a dot pitch between .25 and .28 mm. Similarly, most LCD displays have a dot pitch between .20 and .28 mm. Some high-end displays used for scientific or medical imagery have dot pitches as low as .15 mm. These displays usually cost several times as much as consumer displays of the same size.
While the terms "dot pitch" and "resolution" are related, they have different meanings. A display's resolution refers to how many pixels can be displayed on the screen. For example, a 20" monitor may have a maximum resolution of 1680 x 1050 pixels. When a display is set to its native resolution (typically the maximum resolution), it may display exactly one pixel per dot. However, if the resolution is reduced, the pixels will be larger than the dots used to display the image on the screen. In this case, each pixel is mapped onto multiple dots.