Definition of Interstitial
A display ad that typically appears overlaid on grayed out site content.
Interstitial in Depth
This high impact ad unit is similar to a pop-up ad, except it appears in the same window as the regular site content (many pop-up ads open in a new tab or even in a new window). Because interstitial ads open in the same window as the site content, they won’t be impacted by pop-up blockers.
Interstitial ads are usually accompanied by a “graying out” of the content on the page being viewed in order to drive attention to the messaging of the ad. Below is an example of an interstitial ad unit in action (a link to this page is included in the adjacent table):
An interstitial can also appear over all site content (i.e., without the content visible in the background). In this case, the interstitial is typically accompanied by a link that will close the ad and return visitor to the page they were viewing (a link to the example below is also included in the table):
When to Run Interstitials
Interstitials are high impact ad units, and should generally only be used in special situations. This ad implementation is primarily relevant for sites that are monetizing by selling directly to advertisers. Many CPC ad networks, including Google AdSense, prohibit partners from serving their ads in any sort of pop-up mechanism.
Because the interstitial ad results in a disruption of content consumption, this ad unit must be frequency capped. In other words, many visitors to your site will be willing to put up with an interstitial ad occasionally covering up the content, especially if the ad is relevant and your site provides high quality content. However, even the most loyal of visitors will likely get annoyed if these ads begin appear multiple times during a visit. It is also advisable to avoid showing interstitial ads on the very first page viewed during a session; that initial impression may drive away visitors who would have otherwise engaged with multiple pages on your site.
For example, a publisher may set up an interstitial to run on the fifth page viewed by a visitor, and to only show one interstitial per week.
Including Interstitials on Proposals
Interstitial ad units require additional time to set up properly, and can have adverse impacts on some user experiences. As such, publishers should be compensated with rates above standard ad units.
An interstitial should be viewed as a type of presentation of an ad, meaning that this implementation can be executed on ads of various sizes. Most commonly, a 300×250 or
Finally, it is worth noting that some advertisers may prefer not to have their ads appear as interstitials despite the higher visibility and click rates. Advertisers may be worried about associating their brand with an ad implementation that some visitors will deem to be annoying or invasive. As such, publishers should generally only include advertisers who have specifically approved this type of ad unit.