From Bleeping Computer:
Google announced today [Monday] a shift to “mobile-first indexing,” a move which means that Google search crawlers will look at a site’s mobile version before the desktop one.
This is the result of years of decreasing market share in Internet traffic for desktop devices, with more and more people using mobile devices to surf the web, and indirectly search it.
This change means Google will “use the mobile version of the page for indexing and ranking” on Google Search Mobile.
Until now, Google used content from a page’s desktop version to index and rank websites, but switched links at the last moment to a site’s mobile page if the user was searching from his mobile device.
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More From Google Webmaster Central:
We are notifying sites that are migrating to mobile-first indexing via Search Console. Site owners will see significantly increased crawl rate from the Smartphone Googlebot. Additionally, Google will show the mobile version of pages in Search results and Google cached pages.
Sites that are not in this initial wave don’t need to panic. Mobile-first indexing is about how we gather content, not about how content is ranked. Content gathered by mobile-first indexing has no ranking advantage over mobile content that’s not yet gathered this way or desktop content. Moreover, if you only have desktop content, you will continue to be represented in our index.
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