Mobile websites that push intrusive ads for apps will no longer be considered 'mobile-friendly' by Google.
Google is tackling the practice by some mobile sites using whole-page ads, known as interstitials, that prompt users to install an app. It will use its search engine to penalise mobile websites that use interstitials by excluding them from its definition of "mobile-friendly".
The company introduced changes to its search algorithm earlier this year to encourage companies to build websites customised for mobile displays. Those changes, dubbed 'mobilegeddon', lowered the ranking of sites that failed to meet the standards outlined in its Mobile-Friendly Test page.
The latest change however targets interference when browsing the web on mobile devices.
"Sometimes a user may tap on a search result on a mobile device and see an app install interstitial that hides a significant amount of content and prompts the user to install an app. Our analysis shows that it is not a good search experience and can be frustrating for users because they are expecting to see the content of the web page," Daniel Bathgate, a software engineer in Google's Search team, wrote in a blog post this week.
Google is giving app makers and others that use interstitials within the browser until November 1 to prepare for the changes by adopting less disruptive app-install banner ads.
"Starting today, we'll be updating the Mobile-Friendly Test to indicate that sites should avoid showing app install interstitials that hide a significant amount of content on the transition from the search result page," Bathgate added.
"After November 1, mobile web pages that show an app install interstitial that hides a significant amount of content on the transition from the search result page will no longer be considered mobile-friendly," Bathgate wrote.
He highlighted that the policy change didn't affect other interstitials, for example, those within apps themselves.
The company hinted that changes could be in the works this July when it released a study into its own use of interstitials to promote Google+. It found that on one measure, interstitials were extremely effective, with nine percent of visits to its interstitial page resulting in the 'Get App' button being pressed. However, it also highlighted that 69 percent of visitors abandoned the page, not continuing to the app store, and also avoiding its mobile site.