Google's "Mobilegeddon" is heading your way: The search giant on Tuesday will update its algorithm to give preference to mobile-friendly sites for smartphone or tablet queries.

The change, announced in February, means websites not currently optimized for variously sized mobile devices will be buried under an avalanche of results, while mobile-friendly sites rocket to the top.

The switch threatens a number of sites owned by the European Union, the BBC, and Wikipedia, which failed Google's Mobile-Friendly Test developer tool, BBC News reported.

Similarly, mobile marketing firm Somo suggested famous faces like Versace, American Apparel, Dyson, David Beckham, Microsoft's Windows Phone site, and a handful of U.K.-based services aren't yet ready for the switch.

"When it comes to search on mobile devices, users should get the most relevant and timely results, no matter if the information lives on mobile-friendly Web pages or apps," Google said in a February blog post announcing the update.

Meanwhile, Google last week announced it will no longer show URLs in mobile search results, and replace the domain name with real-world titles. Rather than URLs, Google will display what it calls "a breadcrumbs-like format."

Search "history of Google," for example, and you may find a green line of text reading "Google > about > company > history," or perhaps "Wikipedia > wiki > Google" (above);a set of links akin to a trail of breadcrumbs.

"Well-structured URLs offer users a quick hint about the page topic and how the page fits within the website," software engineer Bartlomiej Niechwiej and product manager Rob Ennals wrote in a blog post.

The Googlers said this change will to help mobile searchers better understand websites. Because if the title link and brief summary aren't enough, you can now look to the green line in between to find more information.

Website developers and owners can indicate their preferred name, and provide more than one possible option, letting Google's algorithms choose between them.

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