Pop-Under Ad

A pop-under ad is one that opens in a separate window of a website that a user has visited. This type of ad does not impede the user’s view of the site they initially visited, but instead opens in the background.

This type of ad was first introduced in the mid-1990s with a set of JavaScripts functions for the Netscape browser:

/ create a new window in front of the current site


// push the loaded advertisement back behind the browser


Pop-under ad vs pop-up ad

Pop-under and pop-up ads serve a similar purpose, but they create a completely different user experience. A pop-under ad opens in a background window or tab, whereas a pop-up ad opens in the same window. Both types of ads are used to entice a visitor to take a further action, like sign up for a newsletter or complete a pending order. Some ad networks don’t make a significant distinction between the two types since they can serve the same type of content.

Pros and cons of pop-under ads

Pop-under ads are generally less distracting for users, which can often create a better user experience than a pop-up ad that disrupts the user’s workflow. Pop-under ads can also generate more high quality traffic than other types of advertising like display ads. They can be configured to open depending on the specific action a user takes, so it’s much easier to target the most likely conversions and measure ROI.

However, many users often perceive pop-under ads as spam and can therefore lose trust in sites that employ a heavy pop-under ad strategy. These types of ads are also significantly less effective on mobile devices, where most users prefer to limit the number of tabs they have open at any given time. Ultimately, the biggest drawbacks to using pop-under ads are the measures most web browsers have in place to block both types of ads. These ad blockers undermine any pop ad use case, which is a major reason why most sites no longer use pop-under ads.

Are pop-under ads effective?

In an ideal scenario, pop-under ads are effective at inviting a user to take a specific action that’s relevant to the content being viewed. However, a shift toward mobile-first web development and the presence of ad blockers on most web browsers have reduced the effectiveness of pop-under ads in most scenarios. Hover and lightbox styles of site advertising are usually more effective than both pop-up and pop-under ads.

This article was updated April 2021 by Kaiti Norton

Webopedia Staff
Webopedia Staff
Since 1995, more than 100 tech experts and researchers have kept Webopedia’s definitions, articles, and study guides up to date. For more information on current editorial staff, please visit our About page.
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