On Friday November 4th 2016 Google announced their long awaited mobile first strategy, confirming your site content MUST BE MOBILE FRIENDLY OR YOU WILL LOSE YOUR RANKINGS. In real terms this means if your site is not mobile friendly you will be ranked below other sites that are mobile friendly. You can read the announcement here. https://webmasters.googleblog.com/2016/11/mobile-first-indexing.html
In a nutshell if a website is mobile responsive and designed so that the same content is shown regardless of the device and the page simply changes to size of the screen, the site will not be affected. However if there are two versions of the same website, one for mobile and one for desktop, only the content that is on the mobile version of the site is indexed by Google. It's as if all the content that's not on the mobile site will become invisible to Google. This pretty big news for the older style sites that separated their mobile and desktop versions. Previously it was perfectly acceptable to have a cut down version of a website just for mobile. But technology has rapidly moved on and mobile responsive websites are pretty much the nrom. This is pretty much a flow on from their announcement last year that they would index mobile friendly sites higher than non mobile sites.
Google are pushing the mobile strategy because the majority of web traffic from Google is mobile.
If you have mobile responsive website, you don't need to do anything. If however your site does not have a mobile version or has am older separate mobile interface you need to update your site to a mobile responsive design. We are recommending that all websites should be mobile responsive to prevent issues with your Google Rankings. If your site is older than about two years it's highly likely that the site will not meet the new Google Guidelines and you should contact our team to discuss upgrade options.