In the early days of the Internet, some computers had video capabilities that were limited to 256-color palettes. Since HTML's 24-bit RGB palette supports 16,777,216 colors, someone very smart figured out an algorithm that reduced the full 24-bit color palette into a much smaller 216-color palette that computers with limited color support could utilize.
Today most operating systems don't have a problem with full 24-bit or 32-bit color palettes, but I tend to stick to the 216-color palette in most circumstances just because it's pretty easy to do the math in my head. When you think about the hexadecimal 00-33-66-99-CC-FF progression, it's pretty easy to figure out which colors you need. That said, every once in a while I need to see the subtle differences between colors that are close to each other. With that in mind, it's pretty handy to keep a color palette around, and the following table lists the original 216-color safe web palette that all browsers should support.
| 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 |
Update #1
I should also mention that sometime back in 1998 I wrote a classic ASP page that automatically generates the HTML for the table that I listed, and here's the code for that:
<%
Response.Write "<center><table border=""1"" cellspacing=0 cellpadding=5 style=""color: #000000; border-collapse: collapse; border: 1px solid #000000; padding: 5px; background-color: #FFFFFF"">" & vbCrLf
Const intFactor = 51
For X = 255 to 0 Step -intFactor
For Y = 255 to 0 Step -intFactor
Response.Write "<tr>" & vbCrLf
For Z = 255 to 0 Step -intFactor
If X < 153 And Y < 153 And Z < 153 Then
strFgcolor = "ffffff"
Else
strFgcolor = "000000"
End If
strBgcolor = Right("00" & Hex(X),2)
strBgcolor = strBgcolor & Right("00" & Hex(Y),2)
strBgcolor = strBgcolor & Right("00" & Hex(Z),2)
Response.Write "<td style=""border:1px solid #000000;background-color:#" & strBgcolor & ";color:#" & strFgcolor & """>"
Response.Write "<tt>" & strBgcolor & "</tt>"
Response.Write "</td>"
Next
Response.Write "</tr>" & vbCrLf
Next
Next
Response.Write "</table></center>" & vbCrLf
%>
Update #2
A lot of web programmers started out with classic ASP like I did, but like most of those programmers I eventually moved on to ASP.NET. And with that in mind, here's the C# code to create the table that I listed:
<%
Response.Write("<center><table border=1 cellspacing=0 cellpadding=5 style=\"color: #000000; border-collapse: collapse; border: 1px solid #000000; padding: 5px; background-color: #FFFFFF\">");
const int intFactor = 51;
string strFgcolor = "";
string strBgcolor = "";
for (int X = 255; X > 0; X -= intFactor)
{
for (int Y = 255; Y > 0; Y -= intFactor)
{
Response.Write("<tr>");
for (int Z = 255; Z > 0; Z -= intFactor)
{
if ((X < 153) && (Y < 153) && (Z < 153))
{
strFgcolor = "ffffff";
}
else
{
strFgcolor = "000000";
}
strBgcolor = String.Format("{0:X2}{1:X2}{2:X2}", X, Y, Z);
Response.Write("<td style=\"border:1px solid #000000;font-size: 11pt;padding: 2px; background-color:#" + strBgcolor + ";color:#" + strFgcolor + "\">");
Response.Write("<tt>" + strBgcolor + "</tt>");
Response.Write("</td>");
}
Response.Write("</tr>");
}
}
Response.Write("</table></center>");
%>