This graph shows you what type of screen size/color your visitors are using. This is essential information for the design of your web site. Make sure that you create your pages using the same equipment as the majority of your visitors. For example, if most of your visitors use Netscape with Windows XP, a 256 color screen and a resolution of 800 x 600, then you need to look at your site under these conditions. Most likely you will be surprised by the result... Don't forget that you are designing your site for your visitors, not for yourself !
Note that only screen size/colors that are used more than 1% of the time appear on this graph. This is done to avoid clutter ; if you need more detailed information please create a spreadsheet file with your complete stats from the main 'check stats' area.