Google believes you'd want to see more mobile-friendly websites when you do searches on a phone or tablet. That's why on April 21st, it'll start giving online destinations with mobile versions higher placements on the results page, assuming you're also using a mobile device. Google's updated algorithm will even parse info from indexed apps, if you have them installed on your phone/tablet and (in case it needs log-in credentials to work) if you're signed in. The company has long given ranking points to websites that are optimized for new computers and devices, and it also made finding mobile-friendly ones easier last year, so the change isn't entirely surprising. If you run a website and need to know if Google recognizes its phone/tablet version, though, you can run it through the company's mobile-friendly test tool. You can never be too sure, especially since the company believes this change "will have a significant impact in [its] search results."