The HTML 4.01 specification defines sixteen named colors, as follows (names are defined in this context to be case-insensitive):

Color Preview Color Name HEX value RGB value
White #FFFFFF 255,255,255
Yellow #FFFF00 255,255,0
Fuchsia #FF00FF 255,0,255
Red #FF0000 255,0,0
Silver #C0C0C0 192,192,192
Gray #808080 128,128,128
Olive #808000 128,128,0
Purple #800080 128,0,128
Maroon #800000 128,0,0
Aqua #00FFFF 0,255,255
Lime #00FF00 0,255,0
Teal #008080 0,128,128
Green #008000 0,128,0
Blue #0000FF 0,0,255
Navy #000080 0,0,128
Black #000000 0,0,0

These 16 were also specified as sRGB and included in the HTML 3.0 specification which noted "These colors were originally picked as being the standard 16 colors supported with the Windows VGA palette." It should be noted that fuchsia is exactly the same as magenta (in the X11 color names) and similarly aqua is exactly the same as cyan.

It should be mentioned that all color values from #000000 - #FFFFFF (16,777,216 colors) are valid.

Nonstandard HTML recognizes other X11 color names, including "orange," "darkgray" (which, ironically, is lighter than gray), "darkorange," "lightgray," "darkgreen," "beige," "tan," "brown" and others.