A banner ad is a rectangular image featured on a website which acts as a portal to the advertiser’s site once clicked on. Whereas original banner ads featured little more than images and text, many of today’s ones are interactive, featuring flash animation, video, and audio to attract the audience’s attention. These ads are a main component of cooperative online advertising and "pay-per-click" advertising, which is unique to the Internet.
A banner ad might use text or sound to beckon the audience to click on or "mouse-over" it in order to effect some change in the ad’s animation. For example, some ads challenge the viewer to click on a moving target or answer a trivia question, thereby engaging the viewer to participate in a game within the ad itself. Moving banner ads, which slide across the screen to attract the viewer’s attention and obstruct his or her view of the web browser, often monopolize bandwidth and are sometimes purposely difficult for the viewer to close. These types of ads are typically seen as an annoying, if not unethical form of web advertising.
Along with direct mail, pop-up ads, and plain text hyperlinks, the banner ad is one of the main models of advertising deployed by websites that wish to advertise their products or services online. Websites that want to use these ads have the option of participating in a link exchange with other websites that generate the type of traffic they want to receive on their own site. For example, a web design company and a tech writer may agree to host a banner ad for one another on their respective sites. Instances where two competing websites participate in an ad exchange, such as a web designer hosting an ad for another web designer, are examples of cooperative advertising.
Pay-per-click advertising is a popular pricing model for banner ads. With pay-per-click advertising, the website hosting the ad doesn’t charge the ad’s owner for the number of people who see the ad, also known as impressions, but rather for the number of times viewers click on the banner ad, known as click-throughs. That way, the owner of the banner only pays for traffic to his or her website, and whatever traffic is lost to the host site is made up for by payment from the owner of the ad.