The good news for advertisers is that banner ads offer the possibility of immediate and detailed information on their effectiveness. Put up a banner ad directing people to your site and you can see in real time whether your traffic is increasing, where it's coming from, whether those new visitors are buying products and lots more. Using this information, offers can be tuned in real time. Not only that but ads can be exposed to people selectively on the Net. It's commonplace at search engines to show ads based on what a user is searching for.
Online stores suggest products based on what that individual has already bought.
The world of advertising hasn't been this sensitive to the market since advertising was done by a live barker extolling the benefits of patent medicines in front of a crowd of potential customers. Immediate and detailed feedback improves advertising. But maybe Web surfers are immune to banner ads. Maybe we've trained ourselves to tune out those annoying animated strips at the top of the page. Change or die.