Can someone please clarify Google TOS and their policy with selling ads on your site? I know your allowed to sell ads on your site as long as they don't look like googles ads, but I have heard you are not allowed to sell back links to other sites. If you are selling an ad then isn't the back link already there? I just want to make sure that there is someway to sell ads without receiving a penalty from Google or a drop in PR, without violating the backlink selling policy. Can someone please help me?