File Under: Glossary

Hexadecimal

The hexadecimal (base 16) number system used for Web-page design consists of 16 unique symbols:0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, and F.

For example, the decimal number 15 is equal to the hexadecimal number F. In HTML, an RGB color can be designated by
RRGGBB
with the first two numerals representing the amount of red, the second two the amount of green, and the last two the amount of blue. If you wanted your background to be red, you could write the code for a body background color as
<body bgcolor="#FF0000">
Black is the absence of all color and white is the presence of all color, so in hexadecimal, black is at the bottom of the system (no red, green, or blue:
#000000
and white is at the top (the maximum amount of red, green, and blue:
#FFFFFF