You might not know what an interstitial ad is by name, but I guarantee you hate them.
They're those obnoxious ads that pop up when you click on a link you want to read, which you then have to close-out—or click through before you get to the content you actually came for. They're another example of a dark pattern, a dirty UI/UX trick that fools users into doing something they don't want to do: in this case, sit through an ad.
Luckily, interstitial ads might be going away soon, because Google's just taken a hard stance against them. On its official Webmaster Central Blog, the Big G says that it will now penalize sites that serve up interstitials to their users in search rankings. Google explains the move this way:
Although the majority of pages now have text and content on the page that is readable without zooming, we’ve recently seen many examples where these pages show intrusive interstitials to users. While the underlying content is present on the page and available to be indexed by Google, content may be visually obscured by an interstitial. This can frustrate users because they are unable to easily access the content that they were expecting when they tapped on the search result.
Pages that show intrusive interstitials provide a poorer experience to users than other pages where content is immediately accessible. This can be problematic on mobile devices where screens are often smaller. To improve the mobile search experience, after January 10, 2017, pages where content is not easily accessible to a user on the transition from the mobile search results may not rank as highly.
Google defines three separate of interstitials it'll be going to war against. There are pop-up ads with a tiny "close" button in the corner you need to click before you can see a site's content; a standalone interstitial you need to click through to get to your page; and a layout that displays a huge, screen filling ad above the fold. It's worth noting that Google will only penalize websites for using interstitials for ads: sites that use interstitials for legal warnings or login boxes will be exempt.
The good news about this move is that there'll probably be fewer interstitials to annoy us, and soon. The bad news? As we've previously shown, while individual dark patterns might fall out of favor, deceptive UI/UX designs will never entirely go away. If interstitials die, another dark pattern will just spring up in its place to annoy us anew.