"Netsafe colors" are colors that display relatively similar in all browsers across all platforms. 24 bit color is really made up of 3 colors Red, Green and Blue each have 256 discrete levels. Colors in RGB mode are created by the combinations that can be achieved when RGB values are set to minimum (0) or maximum (255). Mixing intermediate levels of RGB results in 16.7 million possible combinations. Unfortunately, you cannot be certain that a user can actually see all those colors. To further complicate matters, in HTML colors are usually specified in the Hexadecimal (base-16) counting system. The digits in hex counting are: 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F The hexadecimal system is efficient; 256 values can be captured in 2 places and the 16.7 million combinations of 24 bit color can all be expressed in a 6 place figure such as FFFFFF (white).