If you've spent any time surfing the Internet, you've seen more than your fair share of banner ads. These small rectangular advertisements appear on all sorts of Web pages and vary considerably in appearance and subject matter, but they all share a basic function: if you click on them, your Internet browser will take you to the advertiser's Web site. But how do they work and why are they there?
Banner ads are usually relatively simple pieces of HTML code, but their presence on the Web and their importance in Internet-based business is immense. In this edition of How Stuff Works, we'll examine banner ads and their place on the Internet. We'll see how they work, how advertisers rate their effectiveness, and how you can use them to advertise your site or bring in revenue. We'll also examine the technology behind them and look at some of the different forms they can take. By the end of this article, you will be a banner ad expert!