You're scrolling through your Facebook feed on your phone, and you see an article worth reading. You click the link, but instead of the article you were expecting, a giant full-screen ad prompts you to download the news site's app.
Annoyed, you leave the page. Web. Experience. Ruined.
Those ads are called "interstitials," and they are overly common and widely hated. So why are they still used in Web design and online marketing?
The answer is pretty simple. Interstitials are like billboards on the highway: They put your message in a place where people will be forced to look. But billboards do not actively interrupt the experience of driving, so they're not annoying. Interstitials, on the other hand, bring Web browsing to a dead stop.
Here's the case against interstitials
In 2014, Google felt that interstitials created a poor user experience. Before making the decision to remove them, the company wanted hard data and analyzed its use of interstitials to promote the Google+ mobile app.
Its case study found that interstitials increased bounce rates and had little to no impact on app downloads. Faced with an interstitial ad, 69% of visitors abandoned the page and did not go to the app store or continue to the mobile website.
Google then ran a second experiment to see how removing the interstitial would affect product usage. This time, it promoted the app in a less intrusive way with a smart app banner. After removing the interstitial, one-day active users on the mobile website increased by 17%.