In web jargon, an "interstitial" ad is one that blocks all or most of the content you're trying to look at. They're extremely annoying and are among the most hated type of advertising -- especially when they're on wireless sites.
It's not just consumers who are annoyed. Google is giving publishers until Jan. 10 to get rid of interstiatials or suffer the consequences, which presumably would mean reduced search rankings.
"Google's goal has always been to take their users from A to B as quickly as possible, in a way that best satisfies a user's search intent – basically, 'here is your answer,'" said Mike Dobbs, VP of SEO at the trade conference 360i, according to a report in AdAge.
Dobbs said such ads are "intrusive" and can "create a poor user experience."
In a blog post, Google said there are exceptions, including interstitials to verify people's ages, dialogues to sign into a paywall, and banners that use "a reasonable amount of screen space."
Advertising executives and marketers are generally on board with the change, especially given the growing use of ad-blockers, which strike fear and loathing into the hearts of ad execs.
However, not everyone thinks Google should be the web's standard-setter.
"Many publishers and marketers using interstitials already feel Google meddles with their consumer relationships and of course, don't like that Google is in a position to be judge, jury and executioner," said Kevin Lee, executive chairman and co-founder of Didit, a full-service digital agency that specializes in search, AdAge reported.
Others noted that Google itself serves full-page interstitial ads on its AdMob mobile app advertising network, though perhaps it won't be doing so by next January.