Buzz words such as mobile-first, mobile-friendly and responsive web design have been around for a while now. While we have been able to use tools such as https://www.google.com/webmasters/tools/mobile-friendly/ to see if a site will work well on mobile devices, there is now a new imperative to have a responsive site.
Google has announced a shift to mobile first indexing. What does this mean for a website? It means that search will be ranked first by looking at mobile content. If a site is responsive with the same content on a mobile device as on a desktop, there should be no change in that site’s ranking. However, having different mobile content, in particular less content, could negatively impact ranking.
So, if your website does not use responsive layout, now would be a great time for a website update.