Google has launched a new tool to help you visualize how your visitors view your site.

From Google blog

“In a newspaper, the most important story is featured on the front page. If it’s a really important piece, then it’s placed “above the fold,” which means you can find it on the top half of the first page — the bottom half is folded behind and isn’t readily seen when you first look at the newspaper.

The same concept applies to browsers as well. There’s no clear line for “above the fold” on a browser — there are many different sizes of monitors, browsers are not always full screen and other things like toolbars can take up space. Consider a “Donate” button on a non-profit site. If it’s far down the page, you may not see it when you first view the page. You can of course scroll downwards, but many people don’t scroll and will miss it entirely. For example, on the download page for Google Earth, the install rate increased by 10% when we moved the “Download” button 100 pixels upward. We can attribute that increase to users who wanted to try out Google Earth, but didn’t see the button before.”

It is a great tool to visualize how your visitors will view which ads. It might help you in giving high value ads more prominence as well as help in placing the “subscribe” and “twitter” buttons so as to capture audience attention.