Microsoft announced that it's going to adopt a similar policy to the one Google recently implemented by giving mobile-friendly websites a higher ranking in its Bing search engine.
A few months ago, Google announced that it's going to give a bigger boost to mobile-optimized websites in its own search engine. More and more people visit the Web from their mobile devices, and they are often disappointed to discover that too many websites don't display well on their small screens and are thus harder to use.
Google aimed to rectify that problem by encouraging web developers to care more about how their websites look on mobile. Google promised that it will continue to prioritize overall search query relevance, but if two websites are more or less equal in terms of SEO strength, then the one with the mobile-optimized site will rank higher.
Microsoft has been experimenting with "Mobile Friendly" tags for websites that have appeared in its search engine since last year. What it found is that Bing users can satisfy their information needs faster when the websites are optimized for mobile.
The company has a few straightforward criteria that can help it identify with a high degree of accuracy whether a website is optimized for mobile:
1) Large buttons
The navigation buttons, as well as links and other clickable items, should be large enough to tap. On websites that aren't mobile-friendly, that's usually not the case.
2) Large font
On websites that are not optimized for mobile, the font is usually too small and condensed, and you have to zoom in on the page to see it at a more acceptable size. Microsoft's algorithms can see which websites have a large enough font for mobile.
3) No horizontal scrolling
Many desktop-only websites also force horizontal scrolling for their web pages, which is a dead giveaway that the website isn't mobile-friendly.
Microsoft also checks to see if the websites are displaying content that is compatible with the devices on which they are shown. For instance, this could include Flash content attempting to display on an iPhone. iPhones (or the majority of mobile devices today) can't show Flash content, so Microsoft would mark this as a compatibility issue.
Microsoft will start enhancing the ranking of mobile-friendly sites in the coming months, and in a few weeks it will begin rolling out a tool Webmasters can use to analyze their pages for mobile friendliness.