Google has for some time now been giving ever more weight to websites adapting to any mobile device for their SEO positioning, but it has now issued an ultimatum.
From 21 April, websites that are not responsive (not adapted to mobile devices) will be heavily penalised in Google’s rankings
Google made this announcement on 26 February through its Official Webmaster Blog, “Finding more mobile-friendly search results” stating clearly that websites that are not ready for mobile, on 21 April will lose positioning against other websites that are optimized.

Adaptive or adaptable web design, known as Responsive Web Design, is web design and development that allows web pages to adapt their appearance to the device being used to view them. This technology aims to have a single web design display correctly on any kind of device.
This announcement is historic, since although it was becoming ever clearer that Google rewarded responsive websites, this is the first time Google has officially acknowledged a ranking factor, setting a specific date for updating its always so jealously guarded algorithm.
It is welcome that in this case it is giving notice and setting a deadline for adapting websites that are not responsive, since it lets companies react and make the changes needed so as not to “disappear” from Google.
It is clear that the use of mobile devices (iPads, mobile phones…) is spreading among internet users who visit a website and shop online.
Companies must now make sure their website is responsive if they do not want to “disappear” from Google. It is surprising how major companies and brands still do not have websites optimized for mobile devices.