Google is making changes to the machinery of its mobile searches that will reward websites deemed mobile-friendly and penalize those that are not.
As of Tuesday, Google is updating the way it looks at the design of mobile websites as a way to determine how a site ranks in its mobile search results. The more mobile-friendly the site, the higher it will likely appear in the search results on a mobile device, specifically on a smartphone.
"Today's the day we begin globally rolling out our mobile-friendly update," Google said in a blog post Tuesday. "Now searchers can more easily find high-quality and relevant results where text is readable without tapping or zooming, tap targets are spaced appropriately, and the page avoids unplayable content or horizontal scrolling."
The update affects only search rankings on mobile devices and applies to individual pages, rather than entire websites, Google said. That is, a site may not be mobile-friendly as a whole but still score high in search results because certain of its pages do. But other longstanding criteria could sway things the other way, such as how closely the information on the site matches the wording of your search.
"The intent of the search query is still a very strong signal -- so even if a page with high quality content is not mobile-friendly, it could still rank high if it has great content for the query," Google said.
More often than before, people are searching and surfing the Web from mobile devices -- around, according to a report published in mid-2014 by research firm ComScore. That report pointed specifically to digital media sites, not the Web as a whole. But it does provide a clue to the growing dominance of mobile Web browsing. During holiday shopping season at the end of 2014, meanwhile, nearly 60 percent of Amazon customers .
As such, websites need to ensure that their content can be easily viewed and navigated by mobile users. Through its new search algorithm, Google is offering a wake-up call to website owners. Sites penalized by Google for not being mobile-friendly could find a dip in users and a potentially a dip in sales.
The changes are potentially significant enough for those running websites that they've earned the mock-apocalyptic nickname "mobilegeddon."
"Come April 21, a lot of small businesses are going to be really surprised that the number of visitors to their websites has dropped significantly," Itai Sadan, CEO of website builder Duda, told Business Insider. "This is going to affect millions of sites on the Web."
Google has long been a powerhouse of Internet search on desktop and laptop computers -- so much so that the European Union last week formally accused it ofwhen it comes to online shopping services -- but on mobile devices it has found the going much tougher. In the mobile realm, people tend to reach services through apps and app stores, rather than through an all-purpose search engine.
In 2014, Google's chunk of mobile search revenue fell to 68 percent, down from 83 percent just two years earlier, according to eMarketer.
So the company is making a number of new efforts to boost its appeal to the millions of people wielding smartphones. Last week, for instance, Google tweaked its mobile search capabilities to prompt you towhen content in those apps is relevant to your search..
With new mobile search algorithm going into effect Tuesday, Google gave a two-month warning to help website operators get ready. But some sites, especially smaller ones, may not be aware of the changes or may simply not yet have made mobile friendliness a high-enough priority.
"This change will affect mobile searches in all languages worldwide and will have a significant impact in our search results," Google said in a February blog post announcing the changes.
The update does not address searches done on tablets or desktops, Google said in an FAQ about the mobile-focused changes.
To determine whether a webpage meets Google's new criteria, you can enter its name at the company's Mobile-Friendly Test page. Just type the name of the page, such as cnet.com, and Google will tell you if it's up to par. If it's not, Google will pinpoint any specific problems it finds and even suggest ways to make the site more mobile friendly.
Google did not immediately respond to CNET's request for comment.