"Most of us see display ads every day, but few of us click on them. A study by comScore and Starcom MediaVest found that 84% percent of Internet users never click on an ad. But just because you didn’t click on an ad, doesn’t mean that ad didn’t enter your consciousness. Maybe later that day, or the next day, you found yourself visiting the site that was being promoted in the ad. That’s a view-through visit, or post-impression visit. If you performed an action while visiting the site, that would be a view-through conversion. If you purchased a product while visiting the site, the revenue would be view-through revenue."