Pixel Definition.....

The smallest part of the video monitor display is a small rectangular or square dot called a pixel. The word pixel is a combination of two common words, picture and element. A pixel is best described as a logical, rather than physical unit, because the physical size of an individual pixel is determined by the monitor manufacturer. Pixel size is measured in millimeters (mm).

The specific color of a pixel is a combination of three components of the color spectrum, red, green, and blue. Up to three bytes of data are allocated for specifying the color of an individual pixel with one byte used for each color. A true color, or 24-bit color display system, uses all three bytes at 24 bits per pixel, permitting more than 16 million different colors to be displayed. However, most color display systems use only eight bits per pixel, which provides up to 256 different colors.

The quality of a display system depends on its resolution, or how many pixels the monitor can display, and how many bits are used to represent each pixel. Video Graphic Adapter (VGA) based computers can display up to 640 by 480 pixels, or about 300,000 pixels. Super Video Graphics Adapter (SVGA) based computers can display up to 1,024 by 768 pixels, or nearly 800,000 pixels.