The Browser Palette is the palette used by web browsers to show images on the screen in 256 color modes. If you create bitmaps using this palette, they will not be dithered by the browser when it displays them. If you only use web browser colors (using Browser Palette in the Color Editor or the colors in the Web Browser section of the Color Gallery) and export a bitmap using the browser palette, all flat areas of color will be displayed in 256 color modes without being dithered.