The primary colors of light are red, green, and blue (unlike the primary colors of pigments, which are red, YELLOW, and blue). HTML can request that the browser display any of up to 256 colors per primary color. To calculate the total number of colors that it's possible to choose from, multiply 256 colors times itself for each color: Red x Green x Blue = 256 x 256 x 256 = 16,777,216 total colors to choose from.
But many hand-held devices and some computers can't display more than an aggregate total of 256 colors . Although these so-called 8-bit color displays represent a small percentage of Web devices, they must still be considered when specifying color. To ensure that your colors will look the way you want them to, you should use these so-called "web safe" colors.
Web-safe colors will look about the same on 8-bit color machines as they do on million-color machines. They will also look about the same on PC, Mac, or UNIX machines and will not "dither". There are 216 Web safe colors.
Dithering is what happens sometimes when a browser can't display colors that are not Web safe. The browser display approximates the color by mixing dots of available colors to provide the illusion of a specific color or by displaying broad bands of colors. While this may look acceptable in photographs because they tend to have lots of detail to hide the dithering, it won't look good on large fields of solid color.
In HTML, colors are usually specified using hexadecimal numbers. In hexadecimal numbering 255 is written FF. Here's why:
Hexadecimal is a so-called base-16 numbering system. It consists of the characters 0 through 9 and A through F: a total of 16 digits. Computers like hexadecimal numbers because they are based on bits (2x2x2x2=16).
These are the 16 hexadecimal digits:
0 1 2 3 4 5 6 7 8 9 A B C D E F
The code lists the colors in this sequence: RRGGBB. The highest value of any color is FF. For example, pure red would be FF0000. White is FFFFFF. Gray is 666666. Black is 000000. Web Safe Color Chart with corresponding hexadecimal code
Web safe colors are specified by connecting any three of the following pairs:
00, 33, 66, 99, CC, and FF.
Check the source code for the following:
000000 is black, the absence of any color
6600CC is purple
993300 is light brown
FF00FF is magenta
Make these words the same color as the color they describe. Use hexadecimal code to specify the colors:
Green
Magenta (equal parts of pure red and blue)
Cyan (equal parts of pure green and blue)
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