Optimisation of websites for mobile searches

Google announced in April 2015

that it would be giving preference to sites that are set up for mobile phone searches. So it expects to see a high level of mobile responsiveness, which means for example, that all menus on a standard website, compress nicely into 1 small icon on the top left of the screen containing all the site links.
It also mean that images reduce in size according to the size of the viewport in the mobile phone. It would not be very friendly if you had to keep scrolling and moving the image in your screen to see the site.
It also means that text will display in one column and not 2 or 3, as in standard websites. So when you look at the screen the fonts are far more readable. Yes, we can shows 3 colums of text on a mobile phone, but you have to enlarge to read, and the whole aim from Google’s point of view, is that the user experience be highly user friendly.

There are many tests that can be run to ensure you are mobile friendly.