But the industry is ripe for disruption, and many feel it won't be long before banners are replaced by a better, more attractive advertising solution.
One industry source went so far as to say that we'd one day look back on 2012 and deem it the "defining year in the death of the banner ad."
"The traditional standard media model is challenging," this person said. "There's a lot of pressing need for innovation around the approaches people are taking [to make money online]. I see a lot of people refusing to acknowledge the trend lines here.... 2012 is really the defining year in the death of the banner ad. Other people are refusing to believe it because then they don't have another clear revenue path."
John Battelle, an advertising visionary and the founder of Federated Media, who was present for the invention of the banner ad at Wired, agrees. He told us recently that, as an industry, "we messed up when we decided banner ads would be how we make money on the Web."
"We shoved them up in the corners and tried to ignore them, and advertisers have had to scream from the sidelines," he says. "There's a way to make web advertising a better experience, like an ad in between every pageview that you can simply flick away if you don't want to see it. I'm a big fan of full-page ads, especially on tablets."
"I see a lot of people refusing to acknowledge the trend lines here and are clinging stubbornly to direct sales model," says an industry source. "2012 is really the defining year in death of the banner ad. Other people are refusing to believe it because then they don't have a clear revenue path."
Banner ads achieved mass scale because they're easy to implement on Web pages. Increasingly, their placement is standardized and automated by computers, though big banner-ad deals are still negotiated the old-fashioned way, human to human.
They're also supported by the Interactive Advertising Bureau (IAB), a trade organization whose standards apply to 80 percent of banner ads sold. Battelle, who is on the IAB's board, says he's trying to push the group to rethink Web advertising and come up with a widely implemented solution that makes advertisers look and feel more welcome on Web pages.
The transformation away from banner ads will take a long time. Battelle thinks it could take ten years before the online advertising industry is thoroughly disrupted. In the meantime, more and more companies are steadily working at more engaging banner-ad alternatives.
Foursquare, for example, offers businesses a way to deliver updates to users who use its mobile app to check in to their locations. Facebook and Tumblr offer ad formats that promote specific posts to more users. BuzzFeed tries to create viral stories that feature advertisers. And Twitter's promoted tweets are working well, particularly on mobile devices.
These are so-called native ads that play off user behavior and enhance the experience rather than interrupt it.
Arguably, banner ads tried to do something like that 18 years ago, when every Web page felt fresh and new and the notion of multimedia-rich pages mixing graphics and text were novel.
But the Web has moved on since then. It's time banners did, too.