You define colors in HTML and CSS using either a color name or a color value. HTML supports list of sixteen basic color names. CSS2.1 supports this list as well and adds the color name orange. Most browsers also support an extended set of 140 color names. The following table lists these extended color names, along with RGB and hexadecimal values for each color. The seventeen color names supported by CSS2.1 are highlighted in the table.

GIF images and some older monitors are limited to 256-color displays. To approximate the full palette colors, GIFs and these older monitors will use a process called dithering. To avoid dithering you should limit your colors to a subset of colors called Web-safe colors. The Web-safe colors from the extended color list are displayed in a bold font.