The overview page gives information about the factors to consider when choosing colors for web pages and images.
There's an explanation of what is meant by Web-Safe colors, and how colors in images can be "dithered" when a restricted color palette is in use.
By July 2005, less than 1 percent of the internet population were using 256 color mode (see the stats).
The 3-in-1 color picker allows you to compose colors from the 16 bit Windows palette (65,536 colors). The 4096 color picker uses a range of hex values which can be abbreviated to hex triplets when using Cascading Style Sheets (CSS).
Most browsers recognize 140 color names when used to define colors in HTML tags. The 3-in-1 color picker includes an interactive chart which shows all the named colors.
With the right image tools PNG images can be created that are a much more compact than GIFs. The basic features of PNG ( Portable Network Graphics ) have been supported by browsers since the arrival of Netscape 4 and Internet Explorer 4 in 1997.
PNG offers variable transparency, usually referred to as alpha transparency. Pre-IE7 versions of Internet Explorer for Windows set a gray background to PNG alpha images. It's fixed now.