Precisely what is a "Browser-Safe Color Pallette"?

On the page detailing hexidecimals you can read (or have already read) that any series of hexidecimal numbers and letters (0-9 and a-f) would make a unique color; and this is true....to a point. Of all of the 268435455 possible cominations, only 216 are universally recognized by all internet browsers. If you want to use other colors (#603442, for example, which is a lovely dusty-rose color) feel free, but if the viewer's browser cannot support these "Non Browser-Safe Colors", then either nothing will be displayed, or the browser will use the closest approximation it can find. The later case is usually okay, but the former can be disastrous; I would hightly recommend you select your colors from the pallette to your right --->.