Ad rotation is the practice of showing multiple advertisements in a single location on a web page. Ads may be rotated with each new page load, within a single page load, or both. Because the ads are placed in the same location, they are typically the same format. The goals of ad rotation include: * Allow publishing sites to serve ads for multiple advertisers. * Keep advertising "fresh". If the ad never changes, users are more likely to ignore it. * For content-rich sites, increase exposure to advertising by showing multiple ads per page load instead of just one.