Google is making a big change to its mobile search algorithm Tuesday. It will start giving priority to websites that it classifies as mobile-friendly, ones that have been designed specifically to work on smaller smart phone screens. This could have a huge impact on businesses that don’t have mobile friendly sites. They will now appear lower on search rankings. 

And it’s not just small businesses that haven’t adapted. Large companies including Nintendo, Versace and Kroger all have sites that Google has classified as not being mobile-friendly. 

Google announced the changes in late February to give websites time to redesign. Its announcement warned that this change “will have a significant impact on our search results.”