Brands face a heavy drop in traffic from today, after Google made "significant" changes to its search algorithm to favour mobile-friendly websites. The changes mean the company will now boost sites that display well on mobile devices in mobile search results, and downgrade those that do not. The tweaks mark the biggest change to Google’s algorithm since Panda and Penguin. The company warned that the latest update would have a "significant impact" on rankings, leading some search experts to refer to the changes as "mobilegeddon".