In the early days of web design, there was a lot of fuss about using “web safe colors”. The reason for this was because years ago, many computers had very rudimentary graphics cards – only allowing a set number of colors – 256 – to be displayed. Now, graphics cards are much more advanced, allowing millions of colors to be rendered. So, there’s no reason to limit the colors used to the web- or browser-safe 256 colors.

There’s more information about web-safe colors available here:
http://www.lynda.com/hex.asp