ffffff | ffffcc | ffff99 | ffff66 | ffff33 | ffff00 |
ffccff | ffcccc | ffcc99 | ffcc66 | ffcc33 | ffcc00 |
ff99ff | ff99cc | ff9999 | ff9966 | ff9933 | ff9900 |
ff66ff | ff66cc | ff6699 | ff6666 | ff6633 | ff6600 |
ff33ff | ff33cc | ff3399 | ff3366 | ff3333 | ff3300 |
ff00ff | ff00cc | ff0099 | ff0066 | ff0033 | ff0000 |
ccffff | ccffcc | ccff99 | ccff66 | ccff33 | ccff00 |
ccccff | cccccc | cccc99 | cccc66 | cccc33 | cccc00 |
cc99ff | cc99cc | cc9999 | cc9966 | cc9933 | cc9900 |
cc66ff | cc66cc | cc6699 | cc6666 | cc6633 | cc6600 |
cc33ff | cc33cc | cc3399 | cc3366 | cc3333 | cc3300 |
cc00ff | cc00cc | cc0099 | cc0066 | cc0033 | cc0000 |
99ffff | 99ffcc | 99ff99 | 99ff66 | 99ff33 | 99ff00 |
99ccff | 99cccc | 99cc99 | 99cc66 | 99cc33 | 99cc00 |
9999ff | 9999cc | 999999 | 999966 | 999933 | 999900 |
9966ff | 9966cc | 996699 | 996666 | 996633 | 996600 |
9933ff | 9933cc | 993399 | 993366 | 993333 | 993300 |
9900ff | 9900cc | 990099 | 990066 | 990033 | 990000 |
66ffff | 66ffcc | 66ff99 | 66ff66 | 66ff33 | 66ff00 |
66ccff | 66cccc | 66cc99 | 66cc66 | 66cc33 | 66cc00 |
6699ff | 6699cc | 669999 | 669966 | 669933 | 669900 |
6666ff | 6666cc | 666699 | 666666 | 666633 | 666600 |
6633ff | 6633cc | 663399 | 663366 | 663333 | 663300 |
6600ff | 6600cc | 660099 | 660066 | 660033 | 660000 |
33ffff | 33ffcc | 33ff99 | 33ff66 | 33ff33 | 33ff00 |
33ccff | 33cccc | 33cc99 | 33cc66 | 33cc33 | 33cc00 |
3399ff | 3399cc | 339999 | 339966 | 339933 | 339900 |
3366ff | 3366cc | 336699 | 336666 | 336633 | 336600 |
3333ff | 3333cc | 333399 | 333366 | 333333 | 333300 |
3300ff | 3300cc | 330099 | 330066 | 330033 | 330000 |
00ffff | 00ffcc | 00ff99 | 00ff66 | 00ff33 | 00ff00 |
00ccff | 00cccc | 00cc99 | 00cc66 | 00cc33 | 00cc00 |
0099ff | 0099cc | 009999 | 009966 | 009933 | 009900 |
0066ff | 0066cc | 006699 | 006666 | 006633 | 006600 |
0033ff | 0033cc | 003399 | 003366 | 003333 | 003300 |
0000ff | 0000cc | 000099 | 000066 | 000033 | 000000 |
The 6-character string in each cell of the table is the color identifier. In some of the very dark colors, you may not be able to read the characters, but you should easily be able to figure out the identifier from the pattern in the identifier strings: Each identier is 6 characters long. The first two characters represent the intensity of the red component of the color, the second two characters represent the intensity of the green component of the color, and the third two characters represent the intensity of the blue component of the color.
There are 6 possible values for the different intensities: 00, 33, 66, 99, cc, and ff (in order of increasing value). Thus the color "ffffff" has the maximum intensity value for red, green, and blue -- this is a pure white. The color "000000", on the other hand, has the minimum value for each intensity, and represents black. The color "ffcc33" has as much red as possible, a lot of green, and a little bit of blue. This gives a light orange color.
Every possible combination of the six intensities is presented, giving a total of 6 x 6 x 6, or 216, colors.
The table is arranged in 6 blocks. Each block represents a particular "red" value, and the first block is all colors with the maximum amount of red (red=ff). Within each block, the leftmost edge is the maximum blue value (blue=ff), and the top row has the maximum green value (green=ff).
Netscape picked a set of 216 colors that they felt they could support on most platforms, and advertised those colors as the "web-safe" colors, and the notion has become a de-facto standard.
However, the term "web-safe colors" is a bit misleading, because setting a software standard does not change hardware, and in fact, the actual colors displayed by "web-safe colors" varies significantly from platform to platform. Even so, they do offer one very important advantage: when a web browser displays a "web-safe" color, it does make an attempt to optimize the display for that color. Web-safe colors tend to be pure colors, and as close as possible to the abstract notion of what the color is supposed to be. Consequently, given a choice, web designers always use them.