Google mobile search officially launched the "mobile-friendly" (mobile-friendly) label, and announced that if the seller's website does not have a mobile friendly tag or mistakenly set the mobile friendly tag, then the seller's website will be downgraded.
Google says there are two common smart phone mobile friendly settings errors: One is the wrong redirection of mobile-friendly tags, such as a single page to the seller's website, rather than a specific page of a mobile-friendly version, where possible, Google can try to solve the problem for you, and second, the service " Smartphoe-only is limited to smartphones "errors, such as 404 mobile users, other error pages, error handling googlebot-mobile, or inserting video that cannot be played on a mobile device.
Google Mobile search engine optimization is important for mobile marketing, if the seller's website does not establish the correct search engine, the seller's website can not be in the smartphone mobile Google search results to get a good ranking.
Google: Mobile search official on-line mobile friendly tag