The color depth is an important parameter of the graphic standards. It is the number of possible color or gray values that the color information contains for each individual pixel. The more bits available per pixel, the more different colors can be represented.
With a color depth of 4 bits per pixel, as in the VGA format, one pixel can represent 16 colors, with 8 bits it is 256 colors, with 16 bits it is 65,536 colors, which corresponds to the color depth of Super VGA( SVGA) and Extended Graphics Adapter(XGA), and with 24 bits it is 16,777,216 shades of color.
The color representation with 16 bits is called High Color, that with 24 bits as True Color, that with 28 bits as Direct Color and that with 30 bits, 36 bits and 48 bits as Deep Color.