Source: http://www.free-seo-news.com/newsletter734.htm#facts
On the 12th of May, Google’s John Mueller officially announce that their mobile-friendly algorithm boost has been fully rolled out. This change is supposed to rank mobile-friendly pages better on mobile devices.
It was announced weeks ago that a Google update will be released to help users find more relevant and mobile-friendly pages. Sites that are already mobile-friendly will not be affected.
Google Reminders
* This mobile-friendly ranking algorithm is a page-level ranking signal and does not affect the entire site.
* Pages that are not optimized will not negatively affect mobile-friendly and optimized pages
* The algorithm will only affect mobile searches.
* Make sure your site is mobile-friendly. You can check if it is using this Google mobile-friendly test.
* If your site fails the mobile-friendly test, adjust your website according to the recommended settings and make sure to have a responsive design.